I can't install iOS on iPhone 6 Plus

Look here…

If your iPhone or iPad won't update - Apple Support

Apple_helper_guy wrote:

I think the iPhone 6 is out of support for iOS 16.

iPhone 6 is out of support for iOS 13 and newer, and forever limited to iOS 12.

So, yes, iPhone 6 is also unsupported by iOS 16.

iPhone 6s is out of support for iOS 16 and newer, and forever limited to iOS 15.

arjay0826 wrote:

i can't instoll ios

An iPhone 6 cannot be updated past iOS 12.

Currently, the most recent patch for iPhone 6 is iOS 12.5.6.

I think the iPhone 6 is out of support for iOS 16.