Hi. I've finished my first playthrough and think this would be fun to speedrun. I have seen things about a "prefs.json" file that lets you auto-skip but I can't find it. I have seen the guide but after I open my appdata I cannot find the "TerribleToyboxReturnTo...etc" file. Any help? Am I in the wrong appdata file if that makes sense? All I have found is a "DevolverDigitalReturn...etc" file which is practically empty.

Welcome! I just had a look at my setup and it looks like my Terrible Toybox folder was in AppData\Roaming. From there (hopefully) you'll see the folder and then can go to Return to Monkey Island -> prefs.json.