Question If a point is inside a collider, how do I find how high the point must go to get out of the collider

Could I use raycasts, and somehow set the mask as empty space?

 

Calculate another point that's definitely outside, and raycast toward your point. If it hits your collider, your point is inside. There are edge cases for concave colliders but that solves for most uses. The basic geometry colliders can also return the closest point on the surface of the collider. https://docs.unity3d.com/ScriptReference/Collider.ClosestPoint.html

 

That'll work