Is there a way to add custom functions to vanilla key binds.

I have a working custom flying procedure, it changes the y velocity of the player as long as you hold down the fly key.

The problem is that moving in the air is really slow and you can't really get anywhere like this, so I want to make it so when you're flying and press the move key, you go forward faster.

I already have an idea of the movement part, so all I need is to be able to tell when the player presses the walk forward key.

I would prefer not to make a new key bind and use the prexisting vanilla one.