Apple is reportedly planning to phase out the release of iOS 16 for the iPhone 6s, iPhone 6s Plus and the first iPhone SE. For tablets, iPadOS 16 will not be compatible with iPad mini 4, iPad Air 2, iPad (5th generation), and 2015 iPad Pro models.
Of course, this information is unofficial. Apple will only announce iOS 16 at WWDC 2022. However, the source of information – iPhonesoft – has a good reputation.
If the data is correct, it means that iOS 16 will require the A10 chip as the minimum specification. It’s worth noting that the iPhone 6s and iPhone SE came out in 2015 and 2016, and overall, Apple has been supporting them for a really long time.