[LineageOS Questions & Answers] RockyTV:
Use this thread to suggest features that weren't in CyanogenMOD that you'd like to see in Lineage.

Parenthesized text in italic are my comments regarding the suggestion.

Suggested Features

Built-in system cleaner

Device: request the PIN once a day

Extra support for smart cards

Disable root icon for specific apps

Display network speed in status bar (see EDIT below)

Incremental updates (OP note: this could be handy)

Better app lock (CM had Protected Apps but you can bypass them by clicking on a notification, and you can only lock them with a pattern)

A bunch of features to include in the default launcher

Built in Package Disabler (I think you can just disable the app in the Settings?)

Battery bar

Use substratum theme engine (or at least have better support for it)

Free RAM overview in Recents

Allow any app to run in background

Better support for microG

Stock launcher experience, with more customization options

More lock screen options, like time and weather widgets on lock screen

WebDAV (CardDAV, CalDAV) sync options

Become a fully featured ROM with full F-Droid support

Built-in support for OpenVPN

Autolock phone after call end

Adreno idler

Live Display for all phones (I don't think that's possible because of the sensors each phone has)

Reverse portrait mode

Ship ROM with no apps installed; let the user choose his apps (bit skeptical about this one, maybe we could customize what packages we'd want in our ROM before downloading it?)

WiFi band selection (was removed in Nougat)

Caffeine quick tile (http://lineageos.org/Last-Week-in-LineageOS-5/)

Change DPI settings per app (have different DPIs for different apps)

Better permission handling

Custom date format in status bar

Advanced call blocker and recorder (the latter would be neat to have)

Record voice calls with Voice Recorder app

Backup and restore LineageOS settings (maybe the user could choose where he wants to save the backup file?)

GNURoot Debian support

Gello: update to Chromium v50+ (see EDIT below)

Gello: allow users to choose their download location

Music: add Folder View option

Trebuchet: notification count badge that works like TeslaUnread

Ability to manage certificates

MAC address spoofing

Dialer: option to choose SIM while calling, and to set what SIM to use for each contact

Support for Cisco AnyConnect SSL VPN protocol

Add behaviors for double press, triple press on Home, Back and Overview buttons

Airplane Mode scheduler

Support for dnscrypt

Better built in File browser with local network browsing

One tap toggle for settings tiles

SystemUI tiles

Clear all recents

Add "wave to unlock phone" gesture

Allow users to change SELinux from permissive to enforcing and enforcing to permissive

Night mode tile for Quick Settings

Display Location icon on status bar

Choose which Quick Settings tiles and Power Menu buttons are available when screen is locked

Update unrar and p7zip

Scrolling screenshot and auto enable the navbar when rotating 180°

Display day and month in status bar if date position is set to center

Dialer: option to extend blocking to SMS, block hidden numbers and numbers with prefix names

Trebuchet: option to use Home button to open app drawer

CMUpdater: option to flash additional zips

Add "flip to turn off alarm" gesture

CustomTiles: add Night Mode tile

Option to set different ringtones for different SIMs in dual-SIM phones

CustomTiles: add LTE tile

Add SlimRecents

Solid color wallpapers

Toggle ticker or heads-up notifications

Spam filter for SMS app

Support for EAP SIM protocol to use Mobile Carriers networks

EDIT:

EDIT2: I'm not, in any way, affiliated with LineageOS (nor am I an official developer). I'm a community member just like you are :)