Hi, welcome to the forums!
Do you mean portals as in portal culling? There’s a sample program for that.
Or do you mean portals like in the game Portal? Yes, you can do that in Panda3D. The best way I think to do that would be to set a StencilAttrib that sets a bit in the stencil buffer when rendering the portals, and then, in a new display region, render the scene again, but with a clip plane and a special stencil attribute applied, and from a different angle.
An alternative method is to use render-to-texture. I believe that this method is demonstrated in the example you showed.