On scene load function

I know there is "OnDrawGizmosSelected" and "OnDrawGizmos". (what I'm using atm) Is there a function that can run when the scene first loads in the editor? It's just to make my job a little easier with filling out public functions that then in turn affect gizmos in the game scene.

I know this is even less likely. But what about either "onselected" (in the editor) or better again: when an object's (that has the script) position is changed (either currently picked up and being moved around, or just been dropped so that it runs once.

Does that make sense? Please let me know if you need clarification