can I still use my IPad Air 2 if it’s not compatible with IOS16? Will I get any further updates , last update was 15.7?

1. Yes, except for applications and features which require a higher OS.

2. If you're referring to 15.7(not 12.5.7), you can update to 15.8. An unit on 12.5.7 won't be an iPad Air 2.

(249619)

Still many third party apps avaiable that still support iPadOS 15, but look for this to change as app compatibility will continue to dwindle down, significantly, over the next year, possibly two.

A 2014 iPad Air 2 is, now, nearly 9-1/2 years old, moving toward 10-years old.

So, third party app compatibilty will become more of an issue by the end of 2024.