Help dealing with dynamically changing 2D shape

I'm working on a bullet hell where the player moves inside a rectangle dodging bullets.

The rectangle also has a 2D collider. Easy, no problem as long as the shape of the movement box is a rectangle. But what if I want the shape to change? From a rectangle into a circle, then into a star and other weird shapes, much like you do with vector art.

The player must always be able to collide with it.

I'm not an expert programmer, it would be awesome if there is a way to do it in the editor, maybe the animator, and not strictly in code.

One way I tried to do it is with the Sprite Shape Controller, but unfortunately you can't animate the position of the Control Points

I'm also open to using other software or assets on the Unity store.

Thanks everyone in advance!