I have an old pencil can I use it with my new iPad Air connection don’t match - do I have to buy a new pencil?

The first and second generation Pencil use an entirely different pairing and charging interface. The second generation Pencil can only be used with iPad models that have the magnetic/inductive dock that is exclusively designed for the Pencil. A software update cannot add electronic hardware that the iPad does not possess.

The first generation Apple Pencil, compatible with your old iPad, uses the physical Lightning port for both pairing and charging the first generation Pencil. This pencil can only be used with compatible iPad models that have a Lightning connector.

In summary, the Apple Pencil models are not interchangeable - and can only be used with the iPad that has appropriate internal hardware.

Connect Apple Pencil with your iPad - Apple Support

Apple Pencil compatibility - Apple Support

Yes, you need to purchase the newer 2nd generation Apple Pencil.

The older, original Apple Pencil ( the one with the chrome top cap ) is incompatible with the new 2020 iPad Air 4.

Best of Luck to You!