Overheating
My iPhone X gets over heated when i even use it for few hours what may be the reason and also my battery doesn’t last long.
I am not aware of the ambient temperature in your area --> Keeping iPhone, iPad, and iPod touch within acceptable ...
Low- or high-temperature conditions might cause the device to change its behavior to regulate its temperature. Using an iOS device in very cold conditions outside of its operating range might temporarily shorten battery life and could cause the device to turn off.