Previously, if you wanted to show the remaining battery percentage on your iPhone, all you needed to do was go to Settings > Battery and toggle on the Battery Percentage feature. However, no such toggle exists in the iPhone X. In order to be able view the battery percentage on the iPhone X, you need to follow these steps, as shown by Rene Ritchie via iMore:
Touch your finger to the top right “horn” (or ‘ear’) where the battery icon is.
Now swipe down to reveal Control Center
Screenshot via iMore
The battery percentage will now show on the top right.
Swipe up again to exit Control Center.
While the battery percentage won’t show all the time now like before, it now is just a swipe away. All you need to do is repeat the Control Center process whenever you want to see the battery percentage on your iPhone X. The lack of a battery percentage may be a good thing, as it’ll definitely help you reduce ‘battery anxiety’.