How to make custom Crouched Half Height for prone?

Hi i’m trying to make a prone state with reduced collision. If i reduce capsule half height the capsule reduce from player center which means the player will sink into the ground. Setting the character as crouched and modifying the crouched half height seems to be the best way. The problem is i can only “GET” the crouched half height but “NOT SET”.

Is there any other way to do this?

Also side note how to make physics assets collide with world static?