It depends, I guess. If you’re connected to the Kopia server’s UI itself, you can select all snapshots from all users under the “Local sbapshots” button and go from there. Or, you could create another user account an grant that one access to the user’s data you want to restore and then use that user.
The last part is often a good way to have tests done on say database dumps&backups, to make sure you can restore them and also turn it into a working database again, done from a separate client, preferably using a script that runs every X hours and tests this procedure.