How do I update my version

Go to Settings/General/Software Update and follow the instructions. If it doesn’t offer iOS 14.7.1 but says you are up to date with iOS 13 that means you never removed the iOS 13 beta from your phone. Go to Settings/General/Profiles, tap on the iOS 13 beta profile, then restart your phone to resolve the problem.

And you can’t install iOS 13 on an iPhone 7 or any other iOS device; it is an out-of-date version.

If you're stuck on 12.5.4, you most likely have an iPhone 6 that can't be updated any further.