How do I update my iPhone

What about the iPhone do you wish to update?

For mobile device system software, read this document --> Update your iPhone or iPad - Apple Support

For apps on a mobile device open the App Store app, then Updates, then select the person icon in the upper right corner. Click update All, or scroll down past the first screen to select individual apps.

To upgrade your iPhone hardware, compare models Apple has for sale --> iPhone - Compare Models - Apple