How to access a PS1 disc. Harry Potter PS1 remake

I’ve been wanting to do a “remake” or “expansion” on the PS1 game Harry Potter Philosophers Stone and The Chamber of Secrets as they are two of my favorite old games and I have both of them on disc. I know it’s a bad idea to do remakes of games like this because of copyrights but I’m doing this for my personal use as I’ve always had visions of expanding that game and making it much more bigger giving it a better free-roam as you play the game. So of course I haven’t a clue how to do anything with this engine or to get into this games files so if you guys could direct me or give me some tips that would be great.