Can I update iPhone 7 to iOS 18?

If you want to run iOS 16, you need an iPhone 8, iPhone 8 Plus or iPhone X.

But, it would really make sense to look for a new phone that is 5G capable that can run iOS 18. That would be an iPhone 12 or higher model.

jovet28 wrote:

i want ios16 in my iphone7plus

It's NOT possible. If you need iOS 16 or higher, than you MUST retire your very old iPhone and buy a much newer, more modern iPhone at this time.

If that's what you want then it's time to get a new phone. Newer OS won't support old tech.