Вопрос: Как скачать метапакет?

Лучший ответ:
$ sudo apt satisfy kde-plasma-desktop 

Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
  appmenu-gtk-module-common appmenu-gtk3-module apt-config-icons-hidpi apt-config-icons-large apt-config-icons-large-hidpi baloo-kf5 bluedevil breeze breeze-cursor-theme breeze-gtk-theme breeze-icon-theme catdoc dconf-cli debconf-kde-data debconf-kde-helper desktop-base docbook-xml docbook-xsl dolphin drkonqi
  ffmpegthumbs fonts-hack fonts-noto-unhinted fonts-quicksand frameworkintegration geoclue-2.0 gir1.2-ibus-1.0 haveged ibus ibus-data ibus-gtk ibus-gtk3 iio-sensor-proxy kaccounts-providers kactivities-bin kactivitymanagerd kde-baseapps kde-cli-tools kde-cli-tools-data kde-config-gtk-style kde-config-screenlocker
  kde-config-sddm kde-plasma-desktop kde-style-breeze kde-style-oxygen-qt5 kdeconnect kded5 kdegraphics-thumbnailers kdialog kdoctools5 keditbookmarks kfind kgamma5 khelpcenter khotkeys khotkeys-data kimageformat-plugins kinfocenter kinit kio kio-extras kio-extras-data kmenuedit konqueror konsole konsole-kpart
  kpackagelauncherqml kpackagetool5 kpeople-vcard kscreen ksshaskpass ksysguard ksysguard-data ksysguardd ktexteditor-data ktexteditor-katepart kwalletmanager kwayland-data kwayland-integration kwin-common kwin-data kwin-style-breeze kwin-x11 kwrite kwrited libaccounts-glib0 libaccounts-qt5-1 libappmenu-gtk3-parser0
  libappstreamqt2 libcanberra-pulse libcolorcorrect5 libdbusmenu-qt5-2 libdebconf-kde1 libdmtx0b libdolphinvcs5 libeditorconfig0 libepub0 libfakekey0 libfam0 libgit2-28 libgps26 libgrantlee-templates5 libhavege1 libhfstospell10 libhttp-parser2.9 libibus-1.0-5 libjs-underscore libkaccounts1 libkdecorations2-5v5
  libkdecorations2private7 libkf5activities5 libkf5activitiesstats1 libkf5archive5 libkf5attica5 libkf5auth-data libkf5auth5 libkf5authcore5 libkf5baloo5 libkf5balooengine5 libkf5baloowidgets-bin libkf5baloowidgets-data libkf5baloowidgets5 libkf5bluezqt-data libkf5bluezqt6 libkf5bookmarks-data libkf5bookmarks5
  libkf5calendarevents5 libkf5codecs-data libkf5codecs5 libkf5completion-data libkf5completion5 libkf5config-bin libkf5config-data libkf5configcore5 libkf5configgui5 libkf5configwidgets-data libkf5configwidgets5 libkf5contacts-data libkf5contacts5 libkf5coreaddons-data libkf5coreaddons5 libkf5crash5
  libkf5dbusaddons-bin libkf5dbusaddons-data libkf5dbusaddons5 libkf5declarative-data libkf5declarative5 libkf5dnssd-data libkf5dnssd5 libkf5doctools5 libkf5emoticons-bin libkf5emoticons-data libkf5emoticons5 libkf5filemetadata-bin libkf5filemetadata-data libkf5filemetadata3 libkf5globalaccel-bin
  libkf5globalaccel-data libkf5globalaccel5 libkf5globalaccelprivate5 libkf5guiaddons5 libkf5holidays-data libkf5holidays5 libkf5i18n-data libkf5i18n5 libkf5iconthemes-bin libkf5iconthemes-data libkf5iconthemes5 libkf5idletime5 libkf5itemmodels5 libkf5itemviews-data libkf5itemviews5 libkf5jobwidgets-data
  libkf5jobwidgets5 libkf5js5 libkf5kcmutils-data libkf5kcmutils5 libkf5kdcraw5 libkf5kdelibs4support-data libkf5kdelibs4support5 libkf5kdelibs4support5-bin libkf5kexiv2-15.0.0 libkf5khtml-bin libkf5khtml-data libkf5khtml5 libkf5kiocore5 libkf5kiofilewidgets5 libkf5kiogui5 libkf5kiontlm5 libkf5kiowidgets5
  libkf5kirigami2-5 libkf5konq-data libkf5konq6 libkf5networkmanagerqt6 libkf5newstuff-data libkf5newstuff5 libkf5newstuffcore5 libkf5notifications-data libkf5notifications5 libkf5notifyconfig-data libkf5notifyconfig5 libkf5package-data libkf5package5 libkf5parts-data libkf5parts-plugins libkf5parts5
  libkf5people-data libkf5people5 libkf5peoplebackend5 libkf5peoplewidgets5 libkf5plasma5 libkf5plasmaquick5 libkf5prison5 libkf5pty-data libkf5pty5 libkf5pulseaudioqt2 libkf5purpose-bin libkf5purpose5 libkf5quickaddons5 libkf5runner5 libkf5screen-bin libkf5screen7 libkf5service-bin libkf5service-data libkf5service5
  libkf5solid5 libkf5solid5-data libkf5sonnet5-data libkf5sonnetcore5 libkf5sonnetui5 libkf5style5 libkf5su-bin libkf5su-data libkf5su5 libkf5syntaxhighlighting-data libkf5syntaxhighlighting5 libkf5sysguard-bin libkf5sysguard-data libkf5texteditor-bin libkf5texteditor5 libkf5texteditor5-libjs-underscore
  libkf5textwidgets-data libkf5textwidgets5 libkf5threadweaver5 libkf5wallet-bin libkf5wallet-data libkf5wallet5 libkf5waylandclient5 libkf5waylandserver5 libkf5widgetsaddons-data libkf5widgetsaddons5 libkf5windowsystem-data libkf5windowsystem5 libkf5xmlgui-bin libkf5xmlgui-data libkf5xmlgui5 libkfontinst5
  libkfontinstui5 libkscreenlocker5 libksgrd7 libksignalplotter7 libkwalletbackend5-5 libkwin4-effect-builtins1 libkwineffects12 libkwinglutils12 libkwinxrenderutils12 libkworkspace5-5 libmarkdown2 libminizip1 libnotificationmanager1 liboxygenstyle5-5 liboxygenstyleconfig5-5 libpackagekitqt5-1 libpam-kwallet-common
  libpam-kwallet5 libphonon4qt5-4 libphonon4qt5-data libpipewire-0.2-1 libplasma-geolocation-interface5 libpolkit-qt5-1-1 libpowerdevilcore2 libpowerdevilui5 libprocesscore7 libprocessui7 libqalculate20 libqalculate20-data libqca-qt5-2 libqca-qt5-2-plugins libqrencode4 libqt5concurrent5 libqt5designer5 libqt5help5
  libqt5hunspellinputmethod5 libqt5multimedia5 libqt5multimedia5-plugins libqt5multimediagsttools5 libqt5multimediaquick5 libqt5multimediawidgets5 libqt5opengl5 libqt5positioning5 libqt5printsupport5 libqt5quickcontrols2-5 libqt5quicktemplates2-5 libqt5quickwidgets5 libqt5script5 libqt5sensors5 libqt5sql5
  libqt5sql5-sqlite libqt5test5 libqt5texttospeech5 libqt5virtualkeyboard5 libqt5waylandclient5 libqt5waylandcompositor5 libqt5webchannel5 libqt5webengine-data libqt5webenginecore5 libqt5webenginewidgets5 libre2-5 libscim8v5 libsignon-plugins-common1 libsignon-qt5-1 libsnapd-qt1 libtaskmanager6 libvoikko1
  libweather-ion7 libxcb-composite0 libxcb-cursor0 libxcb-damage0 libxcb-dpms0 libxcb-record0 libxcb-res0 libxml2-utils libzip5 media-player-info milou oxygen-sounds phonon4qt5 phonon4qt5-backend-vlc plasma-browser-integration plasma-desktop plasma-desktop-data plasma-discover plasma-discover-backend-fwupd
  plasma-discover-backend-snap plasma-discover-common plasma-framework plasma-integration plasma-pa plasma-thunderbolt plasma-workspace plymouth-label polkit-kde-agent-1 powerdevil powerdevil-data python3-ibus-1.0 python3-pyqt5 python3-sip qdbus-qt5 qml-module-org-kde-activities qml-module-org-kde-bluezqt
  qml-module-org-kde-draganddrop qml-module-org-kde-kcm qml-module-org-kde-kconfig qml-module-org-kde-kcoreaddons qml-module-org-kde-kholidays qml-module-org-kde-kio qml-module-org-kde-kirigami2 qml-module-org-kde-kquickcontrols qml-module-org-kde-kquickcontrolsaddons qml-module-org-kde-kwindowsystem
  qml-module-org-kde-newstuff qml-module-org-kde-people qml-module-org-kde-purpose qml-module-org-kde-qqc2desktopstyle qml-module-org-kde-quickcharts qml-module-org-kde-runnermodel qml-module-org-kde-solid qml-module-qt-labs-folderlistmodel qml-module-qt-labs-settings qml-module-qtgraphicaleffects
  qml-module-qtmultimedia qml-module-qtqml-models2 qml-module-qtquick-controls qml-module-qtquick-controls2 qml-module-qtquick-dialogs qml-module-qtquick-layouts qml-module-qtquick-privatewidgets qml-module-qtquick-templates2 qml-module-qtquick-virtualkeyboard qml-module-qtquick-window2
  qml-module-ubuntu-onlineaccounts qtchooser qtvirtualkeyboard-plugin qtwayland5 sddm sddm-theme-debian-maui sgml-base sgml-data signon-plugin-oauth2 socat software-properties-qt sonnet-plugins systemsettings user-manager xdg-desktop-portal xdg-desktop-portal-kde xml-core xsettingsd
0 upgraded, 408 newly installed, 0 to remove and 0 not upgraded.
Need to get 190 MB of archives.
After this operation, 788 MB of additional disk space will be used.
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Хотя сравнил с sudo apt-get install --download-only и не заметил разницы в списке пакетов.

но скачиваются не все пакеты((Так понимаю, что скачиваете на другом ПК, а потом переносите пакеты туда, где нужно установить? Возможно, скачиваются не все, потому что часть пакетов на том ПК уже установлена.

Худший ответ:
apt-get download $(apt-cache depends --recurse --recommends --no-suggests --no-conflicts --no-breaks --no-replaces --no-enhances kde-plasma-desktop | grep "^\w" | sort -u)
Но будьте готовы к тому, что там 4000 пакетов, конечно можно --recommends заменить на --no-recommends, но я не гарантирую, что плазма останется рабочей без рекомендуемых пакетов. У меня попытка снести глючащий kdeconnectd привела к глюкам многих других пакетов.