Tools like AltStore or AltServer can sideload IPA files onto your device. Connect your device to your computer, launch AltServer, and follow the on-screen instructions to install the IPA.
For those looking to access YouTube on older iOS devices, such as those running iOS 10.3.4, downloading a YouTube IPA file can be a viable solution. IPA files are essentially app packages for iOS devices, similar to APK files for Android. They can be used to install apps outside of the App Store, which is particularly useful for devices that no longer receive updates or support from Apple. download youtube ipa file for ios 10.3.4