Hi, iPhone 7 can update IOS15?

Your iPhone 7 can update to iOS 15, but you don’t need to update it to transfer its content to a new phone→Transfer data from your previous iOS or iPadOS device to your new iPhone, iPad, or iPod touch - Apple Support

I just was gifted an old iphone 7 by my friend. The software updater updated it to iOS 10.3.4, and it says that it is up to date. How do I get later iOS versions? Thanks.

An iPhone running iOS 10.3.4 can not be an iPhone 7. Instead, it has to be an iPhone 5, which can not be updated further.

Thanks. It seems my friend gave me an iPhone 5, in an iPhone 7 box! We're going to have to have a talk.