I’m assuming the plan is fit her with a laser close-in missile defense system at some point: I see the engines are rated by MW and not horsepower, so the electrical output is what’s important.
The engines are electric that’s why they are rated in that way. This ship generates a lot of excess electricity in anticipation of being fitted with a rail-gun or possibly a laser air defense system. They also did this for every aircraft carrier built since “USS Ronald Reagan”.
When you’re building ships designed to serve for over 50 years you have to anticipate future weapons systems that could conceivably be mounted.