I tried to use a mod from Steam Workshop that would change the size that some airplanes can use.
However after subscribing to the mod only the cargoversions of those planes changed airportsize.
This got me curious, so I decided to look into the modelfiles and see if I could change the size of airport usable just by replacing the line with the size from big to small.
Unfortunately this didn't work since the planes still show large airports in the game despite my change of phrase in the modelfile, so is there anything else I need to look at to change this?