iPhone xr

Assuming there is no damage to the phone see this link and starting at the top (easy) move down by steps to more difficult options to see if you can get your phone going again --> If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support

Have you tried this hard reset?

1. Press and quickly release the Volume up button then press and quickly release the Volume down button.
2. To complete, press and hold the Side button until the Apple logo appears on the screen.

Recently drop the device or gotten it wet?