Why a larger twin-engine carrier aircraft costs deck capacity

Would a larger Royal Navy carrier aircraft built around two F-35B engines be practical?

It might offer more internal capacity, but its width would sharply reduce how many aircraft fit aboard the existing carriers.

The proposed design separates two F-35B engines to create a larger internal bay for fuel and weapons. That arrangement would make the aircraft exceptionally wide while the carrier and its hangar remain fixed in size. The Queen Elizabeth class's twin-island layout might make a hull extension conceptually possible, but cutting and lengthening the ships would be difficult and expensive. Without such a major alteration, each wider aircraft displaces more parked and maintained aircraft. Greater capability in one airframe can therefore reduce the total number embarked.