Activity Rings on iphone

Do you have the Fitness App installed?

If you do and it is not showing, I would delete the app, restart your phone then download and install the app again.

If that doesn't work

I would then un pair the watch from your phone, delete the fitness app and then the watch app, restart the phone.

Download and install the watch app then pair back your watch setting it up as new.

Part of the set up process is installing the fitness app.

Have you paired the watch to the phone?.

Then you can see the rings either by tapping activity app on the watch or by opening the fitness app on the phone.