If you're using Microsoft 365, Exchange.com, Outlook.com, or Live.com accounts that are not accessed by a POP or IMAP, your emails and account settings are backed up online. Offline, you'll only have an OST file. It's not necessary to move this file across computers, as it will be recreated on your new devices. Now, for accounts accessed by POP or IMAP, you can generate (.pst) files with the outlook import export wizard.