I have Xbox One S my friend has Xbox One S. He is in. 1.11.0.7 I am in 1.10.0 It says when I try to join him, he is an outdated client?

You both need to be on 1.10 to play together, your friend will uninstall and reinstall the game to get back on 1.10.

https://twitter.com/MojangStatus/status/1110674379560677377

Or if he already was in the beta by opting in, he will have to enroll from the beta from the xbox insider app