New to the game (and speedrunning in general) and trying to get the hang of the any% route. So far I’ve got the portion up until Crush down pretty well, with the exception of the frog proxy to get onto the platform leading into Crush.

From watching videos it looks like you just have to charge jump into the frog and time it right, but I’ve been struggling to do so. Am I meant to be holding X, or tapping it again as soon as I hit the frog? Or, is it something else altogether?

Yeah you have to press X again as you enter its hitbox. Check out Walkers' run, it has an input display that should shine light on a lot of stuff. https://www.speedrun.com/spyro2/run/mr45nd2z