iphone not showing Battery usage

If you're talking about level percentage:

In the latest iPhone models the notch takes up a lot of space in the status bar at the top, and some symbols/numbers can no longer be shown. To see the battery percentage, you have three main options:

1.      Open the Control Center, swiping down from top right corner of your screen;

2.      Add the "Batteries" widget to existing ones;

3.      Ask Siri: "what’s my battery charge level?"

Choose the most convenient one for your habits.

If you mean something different, please better clarify your needs

Regards

Giulio