Extend iphone to external monitor, rather then simply mirroring the screen

I hope the title is specific enough. In short, I am able to mirror the phone to an external monitor but find the default mirroring far less productive than using the monitor for additional real estate.

I recognize some apps may force the vertical orientation, but ideally want to run compatible apps in the extended screen with either the home screen or a vertical app on the phone screen itself.

Alternatively, I’d also be happier with replacing the builtin display whole sale to only utilize the external monitor without the force letterboxed black bars. In a perfect world the phone could default to a track pad similar to the remote app, but even using the single external screen edge-to-edge beats the default behavior.