Hello UYLC,
Thank you for posting in Apple Support communities. We understand that you are having trouble using the dialer screen on your iPhone 11. We would love to provide you support on this.
We understand that you don't see a cursor when dialing and wanting to go back and make a correction on a number being dialed. Your iPhone 11 running iOS 14 does not offer a cursor to allow a correction it does however offer a back space (delete button) to erase and retype.
The paste feature should work with no errors when pasting in an empty dialing field. If you try to paste in the dialing field when digits are already there it will not function correctly.
This resources tells you how to make a call and the available feature you can use when doing so: Make a call on iPhone
Thank you for allowing us to support you.
Have an awesome and productive day!