My iPhone will freeze if I tap the software update in settings

If you're certain it is a 6S:

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

Why have you hijacked dinopax' thread when you are asking the same question on your own thread?

How can I update to iOS 14 - Apple Community

The iPhone 6+, released by Apple nearly nine years ago, cannot be updated beyond iOS 12.5.7.

is iPhone 6s that am using

I can’t even download some apps because they require iOS 14