I don't know about the coordinate system

Ask a question, after the model is loaded into the scene, is the world coordinate or the local coordinate system, whether the camera exists in the world coordinates or the local coordinates, the position of the current model debug has reached e, then the location is the world location or the local location, When I select the model, I should get the position of a coordinate system with the camera.

I believe this answer fits here as well - Wrong location of model acquisition

You can read about the parenting system here:

https://doc.babylonjs.com/how_to/parenting