If you draw a 3d polygon on a paper then is it a 2d 3d polygon or a 3d 2d polygon?

It's both a 2d 3d polygon and a 3d 2d polygon, since it is a 2d 3d 2d polygon.

By definition, a polygon can only be 2D.

The equivalent 3D object is a polyhedron

You are actually asking about the projection of a 3D *polyhedron* onto a plane. The resulting shape is therefore a 2D representation of that 3D polyhedron.

You can draw a two-point or three-point perspective projection, an isometric projection, an orthographic projection, etc. But in all cases the drawing on the flat plane (paper) is just a way in 2D to represent the original 3D object.

It's a 2D representation of a 3D object, polygon or not.

I don't know what "2d 3d polygon" or "3d 2d polygon" means, but what you have is a 2D representation or mapping of a 3D polygon.

neither, it's a graphical representation of a 3D polygon drawn on a 2D paper.