I just tested createDefaultEnvironment and nothing works as expected or as I think.
The documentation is very poor on the subject, there is no example for the creation of a land and a skybox.
I try many things, but nothing works.
https://www.babylonjs-playground.com/#10D6YT#59
Another example here
https://www.babylonjs-playground.com/#10D6YT#60
I also notice something else with a camera create by default with createDefaultCameraOrLight() The skybox is not displayed if the skybox is over 260 units. If we do a skybox of 500 for example, we do not see it.
https://www.babylonjs-playground.com/#10D6YT#61
Another bug, try to turn the camera and you would see something weird
https://www.babylonjs-playground.com/#10D6YT#62
I have not tested everything, because I have the impression that nothing works as expected and the documentation lacks information on all this.