Can they? As in, is it theoretically possible with current engineering? Sure.

Should they is another matter, and the answer to that is definitely no.

If you look at the new Ford class carriers, you’ll see they’re about the same size as the preceding Nimitz class which has been in service since the 70s.

Nimitz class top, Ford bottom

Why is that? For starters, if you make something significantly larger, you don’t just have to build it. You have to service it too.

To build and service it would require a drydock double the size if you are making it twice the size. That alone would be a major undertaking.

It would surely cost more, and having similar manpower to a ship half the size is not realistic. Just doing maintenance would require more crew for sure. That increases the cost and personnel burden further.

Then, you have to consider that given such a ship would probably use twice the resources, it can still only be in one place at a time. Right now, the US has 11 supercarriers active with one (Nimitz) slated for retirement this year. The fleet plans on having 10 groups in service normally, but you have to keep in mind that not all are at sea at once. At any given time, there’s usually about 1/3 of them at sea, 1/3 at port getting ready to deploy, and 1/3 under repair.

If you can only afford to field half the carriers, this means the impact on those actually ready at any given time is much more severe. It would mean at any given time you’d probably only have 1–2 at sea, which is pretty bad.