Play through the game, export saves at every scene you want to return to and keep them all in a folder on your computer, then you can import them and re-enjoy them whenever you want. Repeat with different choices if you want to see different versions of scenes or different paths. That's the best you're going to get.
There's someone currently
attempting - or at least they were doing so previously, I haven't heard much about their progress recently - to try and make a sandbox version of this game, and it's an absolutely herculean task, and who knows if it will actually ever fully get completed. So you could always wait and see if that ever happens, or you can just enjoy this game as it is, and do what the rest of us do and do multiple playthroughs and make different choices and enjoy the many different possible paths and find new things each time.