Hello,
No, I'm not an Apple employee. You're not addressing Apple here. This is a user-to-user tech support forum and we are just users like you.
That said, if you're sure your iPad Air is a 2nd generation model (you might identify it better by looking at the back cover of your device, and read the "Axxxx" code, where xxxx are four numbers).
An iPad Air 2nd generation model should have one of the following codes: A1566 (wifi only) or A1567 (wifi+cellular).
Should be this case, it should support current iPadOS 14.7.1 version.
But, as you said, if your device is currently running iOS 12.4.1 (a very old operating system version) you might have difficulties to update it wirelessly (via wifi).
That's why I suggested to connect your device to a computer running iTunes (PC) or Finder (Mac), and perform the update procedure that way, as per these instructions:--> Update software on iPhone, iPad, or iPod touch in iTunes on PC - Apple Support, or these:--> Update software on your iPhone or iPad - Apple Support
If you don't have a computer, borrow one from your friends/neghbors, or (better) ask for help at an Apple Store or Authorized Service Provider.
For any further question, you can contact Apple Support directly, using this link:--> Get Support
Thanks and regards.
Giulio