How do I save and work on multiple copies of my developed game?

I tried copy and pasting the exe file but could not restore from it by replacing it. I’m probably missing the answer it’s prob stupid obvious. But I want to work on multiple versions of my project. Setting aside some to come back to later. Advancing others in different direction. How do I save a copy of my project and restore it? If I’ve altered said project in some way.

A software versioning system like SVN, GIT, etc.

Well, in doubt, you can duplicate/clone your projects in your Epic Games Launcher library (via right click), and after that, you probably just have to edit the version number in your project settings.

Not sure, if there is an official way, that autosaves different versions.