I do not know if you can import Outlook Emails into other email clients. I would also from within Outlook export your contacts so that they can be easily imported into your new email client. It would probably be best to do the backup using recovery media to make sure that you have backed-up the current status of your MS Outook data. Do not use libraries use the path name when selecting the data to be backed-up. Make sure that for OneDrive you have deactivated files on demand (all files will then be downloaded) before running the backup. You could also try using ATI 2019 (or earlier) to do a files and folders backup of the relevant directories on the PC. Once you have done so you can download the files to a local PC. This is done without downloading to your PC - it is doen directly between the Microsoft server and the Acronis Server.

With True Image Home 2020 (and 2019 and possibly 2018) you can backup your One Drive and MS Outlook to Acronis Cloud.

It depends on what Acronis product you are using.

Acronis office365 backup