If you watch YouTube more than 2 hours a day, just pay for YouTube Premium. The convenience of seamless updates is often worth the $13.99/month. But if you enjoy tinkering? Grab that IPA and start sideloading.
Developer notes / implementation
takes it further:
In the context of iOS, a is an application package used to sideload the YouTube app onto iPhones or iPads outside the official Apple App Store. This is most commonly done to install modified versions of the app that include features not found in the standard version. 1. Purpose and Common Variants Youtube Ipa File