[Flags]public enum LocalPhysicsMode

By default, when a Scene is created or loaded, any 2D or 3D physics component added to a GameObject within the Scene is added to the default physics Scene. Each Scene however has the ability to create and own its own (local) 2D and/or 3D physics Scene. This option can be used when creating or loading a Scene to specify whether a 2D and/or 3D physics Scene should be created.

When a Scene creates its own 2D and/or 3D physics Scene, the lifetime of the physics Scene(s) is the same as the Scene i.e. if the Scene is destroyed/unloaded then so are any created physics Scenes.

Additional Resources: CreateSceneParameters, LoadSceneParameters, SceneManager.CreateScene, SceneManager.LoadScene and SceneManager.LoadSceneAsync.