Apple Air IPad Latest IOS software

iPad Air can only go up to 12.4.7

Apple security updates - Apple Support

A first generation iPad Air can only be updated to iOS 12.4.7. By contrast, an iPad Air2, or the current Air3, can be updated to the current version - iPadOS 13.5.1

Apple ended major update support for iPad Air1 in September 2019. An iPad Air1 cannot be updated to iPadOS 13 (or any later major versions of iPadOS) as the internal hardware does not meet the minimum technical requirements for new versions of iOS/iPadOS.

Some App developers have dropped support for iOS versions preceding iOS 13.x for technical reasons (often because APIs or software libraries upon which they rely have been updated in the new version of iPadOS, making their App incompatible with earlier versions). 

Whilst many App titles remain compatible with your iPad Air1, if you want or need to access to Apps requiring the most recent versions of iOS, you’ll need to consider replacement of your iPad with a newer or current model that supports iPadOS13.x.

Sorry, I appreciate that this may not be what you were hoping to learn if you do, indeed, possess an iPad Air1.

I hope this information provides helpful clarity as to your available options - and the limitations of your existing iPad Air.

Why?

I am still using my iPad 3rd generation (2012), running iOS 9.3.6.

I cannot get new iOS updates but still usable from what I have already on my iPad.

FWIW, I do have an iPad Pro 12.9 inch 3rd generation running the latest 13.5.1.

That's correct.

To run iPadOS 13.x, device must have A9 processor or later and 2 GB RAM.

iPad Air has A7 processor and only 1 GB RAM.