Re: Autosave
I'm not convinced the auto-save option does anything either but I'm open to being corrected.
To do what you have in mind I think you'd probably need to make a manual copy of your save game file that you could then put back it you wanted to go back and do things differently.
(This is easier on PC or PS4 but on PS5 it could be done using an unsynched cloud save. I know nothing about how save files are managed on XBOX consoles.)