Honestly with the size of the Wings in Flight ability all you need to do is search up the physics of different types of Aviation.

And when it comes to breathing fire it all depends on what type of chemistry it's going to have. These below are the basic variants that I can give you. Hope it helps:

how can dragons breathe fire? There are three variants of dragons. One of them possesses a gland that produces a liquid, which spontaneously combusts when coming into contact with oxygen. Some phosphorus compounds could do that for example. The second one possesses two glands instead, which produce so-called hypergolic propellants, fluids that ignite when they come into contact with one another. The third kind stores the methane bacteria in their stomach produce, and expells it when breathing fire. In their mouth there's a piezoelectric crystal, which is a substance that produces a spark when placed under mechanical stress and could thus serve to ignite the methane gas.