https://www.techradar.com/news/youre-going-to-have-to-wait-longer-for-group-facetime-in-ios-12

Apple's next big software update - iOS 12 - is expected to launch in the next month or so, but the latest beta has confirmed one of the most anticipated features won't be ready to use on day one.

Group Facetime, a feature that allows you to video chat with up to 32 people at once, won't be waiting for you to use at launch and is instead delayed until a future update.