Why didn't you do a yt search to find out videos about hacks/mods for both of those games? In Crash games there are actual new levels iirc.

There was this thing called Spyro 3.5 too some years ago and I even played it to the credits. It has different egg and gem placements, different story with new dialogue and you use speedrun exploits to get to the eggs. Which means it's definitely not for everyone or casual players even because it forces you to try 50 times to learn a big jump etc to get ahead, tho there was an easier version too. I played the normal/hard one, even tho I obviously used save states because I didn't have any previous Spyro speedrun experience so I didn't know the tricks.