I want to upgrade my iPhone

Hello,

It looks like you are using an iPhone 6 Plus, running iOS 12. Unfortunately, the iPhone 6 Plus is unable to install iOS 13 and all subsequent iOS versions. But you are still able to receive security updates from Apple.

I hope this helps!

Jason

You can upgrade your iPhone. You could upgrade a newer iPhone (but only to the latest version of iOS right now). But unfortunately you can't upgrade your iPhone 6 Plus to iOS 13.