Use Screen Mirroring to see the entire screen of your iOS device on your Apple TV or AirPlay 2-compatible smart TV.

1. Connect your iOS device to the same Wi-Fi network as your Apple TV or AirPlay 2-compatible smart TV.
2. Open Control Center:
   • On iPhone X or later or iPad with iOS 12 or later: Swipe down from the upper-right corner of the screen.
   • On iPhone 8 or earlier or iOS 11 or earlier: Swipe up from the bottom edge of any screen. 
3. Tap  Screen Mirroring.
4. Select your Apple TV or AirPlay 2-compatible smart TV from the list.
5. If an AirPlay passcode appears on your TV screen, enter the passcode on your iOS device.

Your TV uses your iOS device's screen orientation and aspect ratio. To fill your TV screen with the mirrored iOS device screen, change your TV's aspect ratio or zoom settings.

To stop mirroring your iOS device, open Control Center, tap Screen Mirroring, then tap Stop Mirroring. Or press the Menu button on your Apple TV Remote.

If you have a Google Chromecast device

You can use a number of third-party apps that will mirror your iOS device's screen to a Chromecast such as Mirror for Chromecast.