Cameras do not have to output directly to the screen all the time. Different effects can be achieved by having the cameras send their output to a Render Texture asset file. In the scene, 3D objects can be linked to a Render Texture asset file, and so the output of a camera can be directed to 3D objects such as Planes and Cubes.

In this recipe, first, we'll duplicate the over-the-shoulder Main Camera child of the ThirdPersonController, and send the output of this duplicate camera (via a RenderTexture asset file) to a plane on one of the house walls. Then, we'll add a different camera facing out from the wall. This is so that our plane will act just like a mirror, rather than duplicating the over-the-shoulder Main Camera: