PolygonCollider2D.CreatePrimitive

public void CreatePrimitive (int sides, Vector2 scale= Vector2.one, Vector2 offset= Vector2.zero);

Parameters

sides	The number of sides in the polygon. This must be greater than two.
scale	The X/Y scale of the polygon. These must be greater than zero.
offset	The X/Y offset of the polygon.

Creates as regular primitive polygon with the specified number of sides.