IOS updating
Is it possible to update an Ipad Air 2 to the IOS 12?
iPad Air 2 Wi-Fi
Question marked as
Yes.
What version of iOS is this iPad Air 2 currently running?
For the next 12 days you can still install iOS 12.4.1 OR I would simply just wait the 12 days and upgrade that iPad Air 2 to the newest iPadOS coming on September 30th.
Depending on what iOS version that iPad Air 2 is running, you may have to connect that iPad to a real computer running the latest version of iTunes to do the iOS upgrade/update.