Here is the list of Apple devices that will get iOS 11
Тhe full list of iOS 11-compatible devices includes the iPhone 5s and newer iPhones, all iPad Air and iPad Pro tablets, the 2017 iPad model, the iPad mini 2 and later models, as well as the 6th generation iPod touch. Here’s is what this list looks like on Apple’s site:
It is interesting to see that the iPhone 5s – a model launched in 2013 – is to be upgraded to the new OS. Android phones, in comparison, get 2 years worth of updates at best. Тhe iPhone 5 and the iPhone 5C are obviously not going to get iOS 11, so if you're still holding on to one of those, perhaps it is time to consider upgrading.
You should have in mind that not all iOS 11 features will be available on the devices listed. The recently announced person-to-person payments, for example, and Apple Pay Cash will be available on the iPhone 6 and later iPhone models, but not on the iPhone 5s.
source: Apple
Things that are NOT allowed: