I'm making this mod and for one race i was going to have a sort of landing craft that could turn and fly then land and produce units

is this possible to do???

Sure.
You can give a building an attack that only activates when lifted off which is probably the easier way to do this.
Or make a siege tank replacement where siege mode is flying, or you can do morphs and so on. There's tons of things you could use to do this.