If you cannot get the phone to power off normally, do a force restart. For a XS press and release the Volume Up button, then the Volume Down button. Then Press and hold the power button until the device shuts off and restarts.
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If you cannot get the phone to power off normally, [link|https://www.ifixit.com/Guide/iPhone+XS+How+to+Force+Restart+iPhone+XS/113914|do a force restart|new_window=true]. For a XS press and release the Volume Up button, then the Volume Down button. Then Press and hold the power button until the device shuts off and restarts.
If you cannot get the phone to power off normally, do a force restart. For a XS press and release the Volume Up button, then the Volume Down button. Then Press and hold the power button until the device shuts off and restarts.