Can I use the Magic Keyboard that I got with my I24 with my IPad Air, 4th generation?

There are two models that came with iMac 24, one without Touch ID and one with.

See: Magic Keyboard - US English - Apple

and

Magic Keyboard with Touch ID for Mac models with Apple silicon - US English - Apple

The Compatibility section of the above two links states that the first one (without Touch ID) is compatible with the iPad Air 4th generation but doesn't say that for the one with Touch ID. I have not personally tried either.

It may still work (possibly everything except the Touch ID). Since you already have one it wouldn't hurt to try it.