IIRC, China has something like 80+ times the shipbuilding capacity of the US. Towards the end of WW2 when the US was kicking the shit out of Japan and obliterating their production capacity, they had something around 9 times the capacity. China's just using it mostly to build container ships, but if they wanted to make carriers (though I have heard people smarter than me say carriers aren't as important as they used to be) they absolutely could. It wouldn't be 100% straightforward because obviously container ships are pretty simple, but it'd be a hell of a lot less of a problem than it would be for the US to spool up production.