I want to upgrade my iPhone software

Update your iPhone, iPad, or iPod touch

• If you have an iPhone 5S or 6/6plus, the highest you can update to is 12.5.6

• If you have an iPhone 6S through 7, you can update to 15.7.1

• If you have an iPhone 8 or higher, you can update to 16.1.2

Go to Settings > General > Software Update.

This link will show you how to update your iPhone, iPad, or iPod touch using WiFi -

Update your iPhone or iPad - Apple Support

This link will show you how to update using your computer -

Update iOS on iPhone - Apple Support

Which device?

iPhone or iPad:

• Software Update.
• Update iOS on iPhone.
• If your iPhone won't update.

Mac:

Click ▶︎ Software Update.

Apple Watch:

Click ▶︎ Software Update.

To have a chance at getting help, more information is needed as to what you're trying to accomplish.

Tips:

Writing an effective Apple Support Communities question