Can I use this apple iOS for I phone 7

You can use iOS 15.4 on your iPhone 7.

Go to Settings > General > Software Update.

Update your iPhone, iPad, or iPod touch using WiFi -

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

Update using your computer -

Update iOS on iPhone - Apple Support

My Phone network got disabled and it is giving error due to IOS upgrade but while trying it not upgrading the IOS 15.4.1

What is the solution to overcome this issue.