How can I update my phone to iOS 15.7

Check if your unidentified iPhone model supports that iOS version in this compatibility chart:

Should be this case, use the following instructions:--> Update your iPhone, iPad, or iPod touch – Apple Support, and/or (if needed) these steps:--> If your iPhone, iPad or iPod touch won’t update

Regards

Giulio

You will need to have a phone that supports iOS 15, which is iPhone 6s and newer.

To update your iPhone, go to Settings > General > Software Update and press download.