National markings for all air forces were to a standard size for a type of aircraft, although there were a few minor adjustments, in some cases, for certain aircraft 'shapes', and specific 'Theater' or recognition requirements, period and location, might dictate changes.
So in most cases, stars and bars, for example, would be the same size on most fighters, larger proportions but the same on bombers, and so on. Again there were exceptions as aircraft got larger, and also 'rules' specific to an air force, where insignia might be a percentage of the area being applied to, for example.
A major U.S. 'exception to the rule', for example, was for the P-47 in the ETO, where over-sized stars and bars were applied to both sides of the bottom of the wing.