BearBear
Archmage
About how large do you envision that a "common" adult dragon will become?
Well my "dragons" aren't typical dragons. Typical dragons should realistically be no bigger than T-Rex if they have sufficient food and range. It would absolutely be believable if they had some evolutionary pressure to grow like giraffes, elephants, etc. Our current Earthly Apex predators are human-sized or below except for in the oceans where say a Sperm whale is massive.
Obviously this is fiction and I will reference Godzilla movies here as an example of potential size, see King Ghidorah.
I'd love to go on and on about my flavor of creature referred to and similar to "dragons", but I don't think that's what you want. However, I will anyway. Mine are more anthromophic but they still have "skin wings" tails, large size, etc. In my case they should top out at 1500 lbs or maybe a ton (1000kg) for an alpha male. No more than 10ft tall or (3 meters). Capable of hunting all but Kodiak Grizzlies in claw to claw combat as they also reach 10ft standing and 1500lbs. (Gee what a coincidence.) They're also intelligent in my lore so that affords them toolmaking, traps, hunting techniques, equivalent to humanoids though claws get in the way. If they could get their claws on guns, they'd probably use modified hunting rifles.
In terms of flight dynamics, that's probably difficult but not impossible for the largest among them though I suspect they'd probably not fly long distances at some point in their adulthood where the fatter of their kind may become flightless and the young fit adults could still fly comfortably but not likely so well for migration purposes. Since they don't have the added benefit that say a pterodactyl or bat would have, given they're 6 appendaged instead of having their arms as wings and webbing from arms to legs. They have classid D&D dragon wings, separate arms, and legs.
Your dragon may vary.