I want to update my software

Hi Euniceapple,

Welcome to the Apple Community.

Below are the various methods of updating iPhone that Apple Support suggests.

How to update your iPhone, iPad, or iPod touch

i.e via internet connection using wifi

Optional: Customize automatic updates

https://support.apple.com/en-us/HT204204

Update your iPhone, iPad, or iPod touch with the Finder

ie: on Mac running macOS Catalina or later.

https://support.apple.com/en-us/HT212185

Update your iPhone, iPad or iPod touch with iTunes

ie on Mac running macOS Mojave or earlier or Windows PC

https://support.apple.com/en-au/HT212186

All the best :-)