The Man the Guns naval system does an awful job representing this.
I respectfully disagree with that verdict. The mission mechanics already support "fleet in being" thinking. Your battleships sitting in port on invasion support contribute to your naval superiority without you having to sortie. Shore bombardment is relevant. I agree that carriers are not represented too well, and AI doesn't know how to use its navy, but the modeling of battleships in that system is very good, I think.
I'd still like an upgrade to carriers but I consider that to be a matter of rather tiny fixes. Enable air sorties when carriers are disengaged, make engaged carriers always try to disengage, include carriers "in range" to all nearby combats (as disengaged). Balance naval targeting and damage output from carrier missions outside naval combat to be possibly just as effective as
when inside combat, up to 100% when enemy fleet is fully spotted (arguably, flip it so there's a penalty when actually engaged). Add carrier strike force mission (sortie just like regular strike force but keep distance).
This chain of really small fixes all work in the current system, produces realistic results, and would make carriers rightful queens of seas.
I do wonder why they took so much effort with that system and then stopped just shy of implementing these details.