I want to update me version

Iphones from 6S and 6S plus onwards can only be updated to ios15

Earlier iphones can only be updated to ios12

Check all of these carefully:-

• you are on a good Wi-Fi, (from 15.4 iPhone 7 up, you may be offered cellular update)

• Plenty of spare storage – 6GB at least.

• on charge with more than 20%, OR

• off charge with more than 50%

• low power mode turned off.

• Fully working cellular network connection via your SIM.

• Check Settings, General to make sure you have no Beta profile installed.

• no VPN installed (Check Settings, General, VPN & Device Management)

Resources:-

Update iphone

Update your iPhone, iPad, or iPod touch - Apple Support

Learn how to update your iPhone via recent Macs here:-->

Update your iPhone, iPad or iPod touch with the Finder – Apple Support (UK)

or older Macs and PC here:-->

Update your iPhone, iPad or iPod touch with iTunes – Apple Support (UK)