You can control this with Wing size or OP costs; that's the best way to deal with the game-balance issues for now.
But here we're touching on philosophical stuff a bit; there shouldn't be "massive" fighters, in the sense of being huge sprites to justify their huge weapons payloads, etc.; fighters are meant to be small, limited and finite assets that feel scaled correctly.
Sprite size is at best an aproximation. Only a tiny bit bigger bomber could easily be (lore-wise) twice as big.
Just take a look at planet scale and distances. Realistic? Nope.
Does anyone care? Not really.
And fighter/bomber size on a carrier will be limited by the carrier itself - hangar facilities, hangar doors/lifts, etc..
The US once used land bombers for a special mission and had them modified and launched from the biggest carrier they had. They barely managed to do it. The bombers had to stay top-side the entire time, since they couldn't get them in the hangar. A smaller carrier couldn't function at all with them.
Adding "size" to a wing would be all that's needed.
Ship_data.cvs wouldn't even have to change, since oyu already have ship size in two variables - mass and type (destroyer, cruiser, etc..)
size 1 - frigate
size 2 - destroyer
size 3 - cruiser
size 4 - battleship
So a size 3 fighter wing could be equipped on any carrier that's cruiser sized or smaller.