Group message contacts
I cannot see other recipients in a group message sent to me on my I phone xs?
If you are not able to see other members of the group gives me an indication that iMessage is not enabled on your device.
On your iPhone, iPad, or iPod touch, go to Settings > Messages, then turn on iMessage. On your Mac, open Messages, then do one of the following: If you're signing in for the first time, enter your Apple ID and password, then click Sign In.
Set up Messages on iPhone - Apple Support