Do I need to back up my iPhone 11 Pro on the cloud before transferring data to a new iPhone 14 Pro?

Well, you should, for extra security, but it you are willing to take chances, no. Just follow these instructions→Transfer data from your previous iOS or iPadOS device to your new iPhone or iPad - Apple Support and hope that nothing goes wrong.

However you SHOULD be backing up your iPhone every night automatically, unless there is nothing on your phone that you wouldn’t mind losing→How to back up your iPhone, iPad, and iPod touch - Apple Support