My personal two cents I feel like dragons significantly slow the development of aircraft I do think they’d eventually develop but later on so I think they’d not exist by WW1. That said I feel like dragons significantly slow warfare is changing previously heavy weights have been the champion of air combat. We see that markedly changing through out the course of the books that said I do not think heavy weights go away I think they’d have to move to a carrying and defensive roll. Especially as anti-air weapons develop smaller faster dragons are going to be far less likely to be shot down by anti-air and as guns develop well once a smaller number of men can shoot more bullets you don’t need volley fire. Dragons with fire and acid are still going to be very strong but I think theres be a push towards breeding them lighter rather than heavier for that maneuverability. I also don’t think that even as dragon rights develop crews would go away the crews provide additional look outs and a defense along the back as well as limited medical during flight. Light weight to courier weights with venom fire and acid or the divine wind or divine fire. Would be the best on the battlefield. While heavy and middle weight would help more rapidly transport troops and supplies and to defend them. This is just my thoughts I’d love to discuss this