Unlike other mobile operating systems, Apple iOS does not respond to touch commands on a certain area of the screen. The battery sign is one area that is not “tappable.”
To make the battery percentage display next to the battery sign, you need to adjust an option via the Settings app. Here’s how to do it, it’s actually very simple.
Note: The screenshots below are taken from an iPhone 8 that runs iOS 11. If you are using a new iPhone X or latest iPhone 11 (which runs iOS 13), The instructions below should also apply. To check what iOS version your iPhone is with, go to Settings > General > Software Update to find out.
Step 1: on your iPhone, tap on the Settings app, then scroll down and find Battery, tap on it.
Step 2: Tap on Battery Percentage to swipe the button from left to right (with the background color from gray to green). Now see the percentage show up? In my case, it shows “100%”.
Done, that’s it. If you want to hide the percentage, just tap on the Battery Percentage option again to disable it.
Pro tip: in case you are interested, you can save some battery and reduce power consumption by turning on the Low Power Mode here as well. See this screenshot.
I hope you find my answer helpful, and let us know if you have any additional questions.