I can’t update my phone software
my Software needs update and I can’t
iPhone 7 Plus, iOS 11
Question marked as
If, as you stated, your 7+ model is still running iOS 11, most likeky you won't be able to update it wirelessly (via WiFi), since the iOS version running on it is too old. You should try to update that device using a computer running iTunes (PC) or iTunes/Finder (Mac).
If you don't have a computer, borrow one from your friends/neighbors or ask for help at an Apple Store or Authorized Service Provider.
Regards
Giulio