How to update iPhone 6s to iOS 16.0
How to get iOS 16.0 from iPhone 6s
Question marked as
You can't. iOS 15.8.3 is the last version your iPhone can run.
For the future, it's impolite to tag onto someone else's thread with an unrelated question. It's much more polite if you start your own thread when you have a question. Plus you're much more likely to get a quick and accurate response if you do.
Regards.