Why my battery percentage doesn’t show

Go to Settings > Battery, then turn on Battery Percentage. On an iPhone with Face ID, the battery percentage appears inside the battery symbol on the status bar. Tip: On iPhone models with Face ID, you can also swipe down from the top-right corner to quickly view the battery percentage in Control Center.

Show the iPhone battery percentage - Apple Support (IN)

Parts and service history

With iOS 15.2 and later and iPhone XR, iPhone XS models, and later—including iPhone SE (2nd and 3rd generation)—you can go to Settings > General > About for the parts and service history of your iPhone. You can also find out if the battery has been replaced. If the replacement was done using genuine Apple parts and processes, "Genuine Apple Part" will appear next to Battery.