Hey There,
If you mean screen sharing by FaceTime follow the instructions ⬇️:
Share your screen
- During a call in the FaceTime app
on your iPhone, tap the screen to show the FaceTime controls (if they aren’t visible), then tap
. - Tap Screen Sharing, then tap Share My Screen.
- A countdown from 3 to 1 appears at the bottom of the screen before screen sharing begins.
Tip: During a one-to-one FaceTime call, a participant who is using an iPhone or iPad can tap, draw, or write on your screen to call your attention to a specific area. The circle, drawing, or writing disappears after a few seconds. If you need more help, you can also allow the other participant to control your screen.
To stop sharing your screen, tap
, then tap Stop next to Screen Sharing. Ending a FaceTime call also ends screen sharing.
if you mean screen mirroring follow the instructions below ⬇️:
Stream video manually from iPhone or iPad
- Connect your device to the same Wi-Fi network as your Apple TV, AirPlay-compatible smart TV, or Mac.
- Find the video that you want to stream.
- Tap the AirPlay button
. In some apps, you might need to tap a different button first.1 For example, in the Photos app, tap the Share button
, then tap the AirPlay button
. 
- Choose your TV or Mac from the list.

To stop streaming, tap the AirPlay button
in the app that you're streaming from, then tap your iPhone or iPad from the list.
For more info visit ☞ Use AirPlay to stream video or mirror the screen of your iPhone or iPad - Apple Support
If you mean another thing let us know!
All The Best.