Your iPhone can stream entertainment from dozens of sources like Apple TV, Netflix, Max, and YouTube. But you don’t have to settle for watching on your iPhone’s little screen. Your iPhone can stream (mirror or cast) movies, TV shows, and some apps (like YouTube) to a TV.
Your iPhone and the receiving device must be signed into the same Wi-Fi network.
You can mirror your iPhone to an Apple TV and some smart TVs. This mirrors whatever is shown on your iPhone screen.
You can “cast” a video from some apps to a TV with Chromecast or smart TV. Casting works within an app and only casts the content of the app (as opposed to mirroring).