Screen share using FaceTime
Should you want to share what’s on your iPhone, iPad or MacBook screen with a friend who isn’t nearby, you can use the latest version of FaceTime which supports screen sharing.
Sharing your screen can be great when you need to troubleshoot for a friend, want some assistance when they aren’t nearby, or presenting content to others.
Screen-share FaceTime on iPhone/iPad
To start sharing your screen, launch FaceTime on your iPhone/ipad and make the call to another FaceTime user. after the call has been connected, tap on “Screen Sharing”. you’ll find the button in the toolbar section, being a rectangle with a person in front.
after pressing the button, tap “share my screen” on the pop-up window. Once the screenshare starts, you can show all parts of the iPhone/ipad (including certain apps). your friend will be able to see exactly what you are showcasing.
once your ready to stop screensharing, tap the button to end the screen share, or simply end the call.
FaceTime on MacBook screen share
open FaceTime app on your MacBook to initiate the call. Once connected, click on FaceTime in the menu bar (located on the top of the screen) and click share (rectangle with a person)
You’ll then be presented with the option to share a particular window or the entire screen. Once your finished, click on stop screen share, or simply end the call.
Source and further reading: https://www.howtogeek.com/804184/how-to-share-your-screen-using-facetime/