How will I fix my disable iPhone XR

If you're asking about your face ID being disabled, go back and read the information in the page you just came from.

If you forgot the passcode on your iPhone, or your iPhone is disabled or unavailable -

How to reset your passcode without a computer if you have iOS 15.2 or higher.

https://support.apple.com/en-us/HT212951

How to reset your passcode using a computer.

https://support.apple.com/en-us/HT204306

If you are referring to your iPhone being disabled for Face ID, then the support article you arrived here from should provide you with the steps to try to resolve this issue. Alternately, you can contact Apple Support directly. To do so, simply select the "Get Support" link in the upper right-hand side of this forum's web page.

Contact the Genius Bar

Genius Bar Reservation and Apple Support Options - Apple

I already provided you with how to do so. Look for the "Get Support" link in the upper right-hand side of this web page.