My Iphone XR is acting up, I cant not hear the person calling me

Have you tried speaker mode? Also, try going to Settings > Sounds (or Settings > Sounds & Haptics), and drag the Ringer and Alerts slider back and forth a few times. If you don't hear any sound, or if your speaker button on the Ringer and Alerts slider is dimmed, your speaker might need to be fixed. If this still doesn't work then try cleaning the speakers/check if there is any foreign object/dirt inside of the speaker area. Make sure your ringer is on.

This information was found from the Apple support page you can view it here:

https://support.apple.com