my iPhone XR won't force reset. All the apps are completely frozen.

Keep trying the forced restart. If you see the slide to shut off bar at the top of the screen, just ignore it and keep holding the side button until you see the Apple logo.

Press and quickly release the Volume Up button. Press and quickly release the Volume Down button. Then press and hold the Side button until you see the Apple logo. This is where to ignore the slider to shut off if it appears on the screen.

If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support

About iOS performance on your iPhone, iPad, or iPod touch - Apple Support

Take a look at the third suggestion in this support article that Chris posted for you in the response above.

If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support