Hello, I am looking for someone that can help me find a way to have a spiral that can tighten.

I can create a circle sketch and go into curves/ helix and spiral to make it but from there I am stumped.

All I really need is for it to tighten /loosen from outer end point. I imagine it is something to do with the radius.

Attached is quick idea of what I am trying to tighten/loosen.

Any idea would be greatly appreciated!