On my iPhone 15 Pro, in My System Settings I have no control of anything in there. It’s telling me to sign out and sign back in to have access to my system settings. It keeps repeating the same messages. Even when I go to Manage it won’t let me sign in. But on my iPad I can sign in and go into my settings. I made sure both my iPhone and S2 app were updated to the latest version. I deleted and reinstalled the Sonos app on the phone. The messages says… “Sonos” Wants to use “Sonos.com” to sign you in. This allows the app and website to share information about you. I hit continue and sign in…. Next message says Sign in as the System Owner, To manage these settings, sign out and sign back in as the owner of this system. It’s on repeat. It won’t let me sign in on my iPhone. Is this part of the update from many months ago. The crazy ass updates that messed everything up? Again, no issues with my iPad. 
I recently added the Arc to my TV Room and had no issues using my iPhone a week ago. I wanted to Trueplay my PlayBase which I added to my Bedroom TV. It would let me use Trueplay on my phone. I had to use my iPad.