Newer Apple devices, the iPhone X, iPhone XS, iPhone XS Max, and iPhone XR don't have a home button and feature new side buttons with unique functionality, so Apple has introduced a new method to force a restart Quick.
It takes a unique combination of pressing buttons to get your iPhone to reboot, and while it's not immediately obvious, once you've learned the steps, a forced restart is the fastest way to restart your iPhone if it's malfunctioning.
frozen screen
unresponsive screen
It does not turn off
how to turn on iPhone X
Solution
First, make sure your iPhone X is fully charged and that it's not just a dead battery causing the problem (if you can't turn it on)
If your screen is frozen and you can't turn off your iPhone X, you can force it to restart by doing the following:
To force restart your device, press and release the volume up button, then press and release the volume down button, then press and hold the side button until you see the Apple logo.
The device will display the Apple logo and then reboot
If forced restart doesn't work, you can try to restore your iPhone X using recovery mode (click here for steps)
If none of the above solved your problem and the screen still doesn't respond or freezes, then you will need to take your device to the Apple Store as it could be a completely depleted battery problem or a physical problem with the device.