Can’t find friends

Are you subscribed to Apple Music? If so, have you set-up a profile?

Join Apple Music on your iPhone, iPad, iPod touch, Mac, or PC - Apple Support

See what friends are listening to in Apple Music - Apple Support

I’d try checking for iOS updates, I’d force-quit the Music app, and would then reboot the iPhone, and see if any of that then gets you the see what friends button...

It’s not necessary to have a profile to get the see what friends are listening to button, but if you don’t have a profile, then clicking on that button will launch the profile setup... (Alternatively, see the previously-linked See What Friends... article.)

Have you tried signing out of and then back in, or signing into your Apple ID if not already signed in, at the bottom of the Music App settings page?