Why I can't update my iPhone?
[Re-Titled by Moderator]
[Re-Titled by Moderator]
Your phone is too old to be updated past iOS 12.5.4
You can keep asking, but there is NO update for your phone. If you need the newer iOS versions, then it's time to buy a newer iPhone which can run them.
There is no update available for that model.
Update iOS
You also cannot update iOS using Personal Hotspot even with a compatible iPhone 6s or newer models.
Why I can't update my iPhone?