If you want to get done sooner, then the fastest way is by updating with a Mac or PC through Finder/iTunes. The easiest way is definitely over-the-air, but it isn't always the fastest. Simply connect your iPhone via USB and head to Finder on MacOS Catalina and newer. If you have limited space on your device or Software Update isn't working for whatever reason, you can update using your Mac.
How to install the iOS update using your Mac
