Can I update my iPhone 6 to iOS 14?

The iPhone 6S can be updated to iOS 14.

The iPhone 6 can not be updated beyond iOS 12.4.8.

why? I really need iOS 14 but I only have Iphone 6 here

Because the iPhone 6 hardware is missing features required by iOS 14.

The hardware inside your iPhone 6 is not suited to run iOS 13/14 efficiently. It is hardware limited.

Axel F.