My iPad Air won’t update to ipados 15

Your iPad lacks sufficient RAM to run anything higher than iOS 12.5.5. Even if you could somehow get iOS 13, your iPad would be unable to run it, meaning you'd end up with a device which doesn't run well, if at all.

Time to upgrade to a newer, more modern iPad at this point.

The first gen iPad Air cannot update beyond iOS 12.

~Lyssa

No. Apple determines the last update for an iPad, and iOS 12 is the final version for that iPad.

~Lyssa