how to change the touch sensitivity?

* These iOS devices support 3D Touch: iPhone 6s, iPhone 7, iPhone 7 Plus, iPhone 8, iPhone 8 Plus, iPhone X, iPhone XS, iPhone XS Max.

Change 3D Touch sensitivity on your iPhone

You can change the amount of pressure you need to activate 3D Touch.

You can adjust the sensitivity of 3D Touch on devices that support it.*

Go to Settings > General > Accessibility > 3D Touch and use the slider to select a sensitivity level. On the same screen, you can turn 3D Touch off and on.

Change 3D Touch sensitivity on your iPhone - Apple Support

https://support.apple.com/en-us/HT205056

You can't adjust the sensitivity on the XR, as it has Haptic rather than 3D Touch. At best you can enable Touch Accommodations.. Settings > General > Accessibility > tap on Touch Accommodations.