My iPhone is on blank screen I can’t turn off to reboot

Try a "forced" restart of your XR, using these instructions:--> Force restart iPhone – Apple Support

If the issue persists, it might be a hardware glitch. Make an appointment and have your iPhone inspected at an Apple Store or Authorized Service Provider. After checking it out, they'll give you all the available options.

Regards

Giulio

First try a forced restart

https://support.apple.com/guide/iphone/force-restart-iphone-iph8903c3ee6/ios