Catapult type does not determine carrier size

Would internal-combustion catapults make smaller aircraft carriers viable by preserving turbine steam?

Not by themselves; air-wing size, aircraft dimensions, and the number of continuously maintained missions are the dominant drivers of carrier size.

Smaller carriers are viable when assigned limited missions, but their size follows the aircraft and the number of simultaneous roles they must sustain. The panel illustrates this with an eighteen-aircraft planning unit: four flying combat air patrol, four ready on deck, additional aircraft in the hangar or maintenance, and reserves for losses and unserviceability. Changing catapult technology does not remove those operational arithmetic constraints.