Spain and Australia are building a ship that may be what we are looking for, it is a LHA about 1.5 billion CAN. Here are the specs,
Length 230.8m
Beam 32.0m
prop to flight deck 27.5m
full load displacement 27,079t
powerplant Gas turbines electrical (pods)
speed max 21 kts empty, 19.5 kts full...