Oculus MetaQuest 2&3 VR and MR environment changeability

We are planning to develop unity programs via Oculaus MetaQuest 2&3,

Can i use both environment via this device? - (Asking about both modes are available in this device)
In Unity Scenes, can i change the specific scene as a VR mode and other Scenes as MR mode?

I need this make specific scene as black that can't render the real world's stuffs and environment,
But Other scenes can be rendered through real world.

I need accurate information to buy this device, thank you