Why a stronger Argentine carrier force still faced submarines

Would an Essex-class carrier with modern escorts and aircraft have changed the Falklands War for Argentina?

Not decisively; the carrier would still have faced British submarines, including boats positioned to attack it.

An Essex-class carrier with Phantoms and Spruance-class escorts would be formidable in isolation, but British nuclear submarines were already tracking the Argentine carrier force. Conqueror was not the only submarine in the theatre, and the newer S-class boats posed a direct threat to any carrier that moved into useful range. A stronger air group would therefore remain constrained by the undersea threat. The counterfactual turns on whether the carrier could survive long enough to use its aircraft.