An Exchange user asked a question:
Is it possible to automatically delete items older than a specific age, let's say 3 years, from the archive? I'm looking at retention tags but I'm not seeing any options to do so. The items are moved to archive after 2 years, and then after another year, I'd like to delete from the archive.
While you can’t have different tags on a mailbox and on the archive, you can apply both an archive and a retention tag to the mailbox, each with a different duration. For example, you can apply both "2 years move to archive" and "3 year delete". After two years, the messages should be moved to the archive mailbox, and after one more year they will be deleted.
To create new tags in Office 365, log into the Exchange Admin Center, Compliance Management, Retention Tags.
As I mentioned, you cannot apply separate tags to the archive only. From Retention tags and retention policies:
"When the user applies a personal tag to a folder in the archive, if a folder with the same name exists in the primary mailbox and has a different tag, the tag on that folder in the archive changes to match the one in the primary mailbox. This is by design to avoid any confusion about items in a folder in the archive having a different expiry behavior than the same folder in the user’s primary mailbox."