Why won’t my phone screen rotate even with lock off

Does NOTHING rotate, or just some things? Please note that not all apps are coded to rotate, even if rotation is unlocked. For example, open the photos app. Can you rotate a photo? If yes, there is nothing wrong with your phone. But if you are using a 3rd party app, which wasn't coded by app developer to rotate, it simply won't rotate.

Most likely a defective screen....specifically the digitizer.....if you know that the app you are using has a rotation option. That XR may be as much as 5+ years old.

As a last resort, try a Forced Restart on the phone. Follow the instructions very carefully, as this is a bit tricky. You may need to repeat this several times.

Force restart iPhone - Apple Support

There are only 2 possible results when you perform a Forced Restart:

1) The phone returns to normal operation.....or, if it doesn't.....

2) There is a hardware problem with the phone that will need attention at the Apple Store (make an appointment) or take the phone to an authorized Apple Service shop.

You can find a list of authorized service shops in your area using the link just below:

Find Locations

It could depend on what you are attempting to rotate. The lock screen and home screen will not rotate. Not all apps will rotate either. You say that you have already turned off the orientation lock, so my guess is the app you are attempting to rotate won't rotate.