How can I see the battery charging percent on the screen

You can add the battery widget...

Add widgets on iPhone - Apple Support

Hi,

Swipe down from the top right corner to see the battery percentage.

https://support.apple.com/en-us/HT201102 << Show the battery percentage on your iPhone, iPad, or iPod touch

On iPhone 11, to see battery %, you need to access the Control Centre.

But you can add a Battery Widget to Home Screen where you can set to see battery %.