How do i display battery life as a percentage??

There is no option to display it permanently at the top of the screen. You can swipe down from the top right corner of the screen to open Control Center and view it there or you can install the Battery widget to display it constantly on the home screen. See: Use widgets on your iPhone and iPod touch - Apple Support

The notch doesn’t allow enough room for required icons and a battery percentage readout. Also, keep in mind that the battery percentage is an estimation of electrical pressure and isn’t going to be exact anyway.

coburn ~ Here's how to add Apple's "Batteries" widget to your iPhone 13 Pro's Home Screen:

Use widgets on your iPhone and iPod touch

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You don't.

You can see it as a percentage in control center, but you can't display it as a percentage on the Home Screen.