To update my 6s plus to iOS 15.6.7
How to update my 6s plus to iOS 15.7
iPhone 6s Plus, iOS 13
How to update my 6s plus to iOS 15.7
iPhone 6s Plus, iOS 13
You cannot pick and choose an iOS version. What you get is Settings > General > Software update > [All options are available here]
You need to correctly Identify your iPhone model - Apple Support
These are the iOS options based on an iPhone Model
Know how to...
You can't.
To update my 6s plus to iOS 15.6.7