Need to implement two Skyboxes in one scene.

My game requires the screen to be split up into two halves and use one skybox for the first half and the second half below the screen is another world, where another skybox has to be implemented.

the player can even switch the world meaning the skybox can also come upside down.

You have two options for implementing Skyboxes. You can add them to an individual Camera (usually the main Camera) or you can set up a default Skybox in Render Settings’s Skybox Material property. The Render Settings is most useful if you want all Cameras in your scene to share the same Skybox.

Adding the Skybox Component to a Camera is useful if you want to override the default Skybox set up in the Render Settings. E.g. You might have a split screen game using two Cameras, and want the Second camera to use a different Skybox. To add a Skybox Component to a Camera, click to highlight the Camera and go to Component->Rendering->Skybox.