A Hard Reset may be required when apps are not working properly, the phone has become unresponsive or other similar issues.
Performing this action will not affect any data on the device.
Because the iPhone X series does not have a home button, these devices require you to hold two buttons to display the power off options.
This can be done by:
1) Press and release the Volume Up button then
2) Quickly press and release the Volume Down button.
3) Then press and hold the Side button until the until the Apple Logo appears
The power off options will then be displayed - continue to hold the Side button until the Apple Logo appears
Once the Apple logo appears your phone will restart and turn back on.