How do I show battery percentage use in upper right corner?

You cannot. There is not sufficient room to display the battery percentage on the status bar due to the notch. To see your battery percentage, swipe down from the upper right corner to see Control Center, and the battery percentage is there, or you can put the battery widget on your home screen.

Unfortunately, there is only so much that can be visible in that area, so given that the battery icon is there and the ease of swiping down Control Center, both directly from the lock screen or any other screen, it was the best they could do. You can also have a widget, which is how I display it on my iPad, because that is much easier to read those larger numbers.

You're welcome.