Is Miracast a supported screen mirroring platform
can I stream to a new sony tv
Miracast support will depend on the specific App, its not natively supported on iOS. Things like Youtube can cast to Miracast and ChromeCast devices for example.
Alternatively, if your Sony TV is one of the supported models for AirPlay 2, you can use Airplay 2 to screen mirror. See the Airplay 2 Compatible device section here: link-> Apple TV app - Devices - Apple