How would a Queen Elizabeth-class carrier rank in 1940?

Would a Queen Elizabeth-class carrier count as a light carrier in a Second World War setting?

No. It would be an enormous super-fleet carrier, though its modern machinery would complicate fitting period catapults.

A Queen Elizabeth-class carrier would dwarf every 1940 fleet carrier and could hold roughly ninety period aircraft. Her long deck would give many piston aircraft enough run to take off in favorable conditions. Launching such a large group efficiently would still require a catapult compatible with Second World War technology. Because the modern ship's machinery does not provide steam, the conversion would need a separate steam plant or a hydraulic accelerator.