You're probably thinking of the real giants that have their own zip codes and internal train systems. The largest airports in the world by land area are absolutely massive some spanning over 70 square kilometers with multiple runways that feel miles apart. These aviation cities handle millions of passengers while maintaining huge operational areas. There's a cool visual breakdown of these colossal hubs at this link https://getrentacar.com/en-US/news/post/the--top-10-biggest-airports-in-the-world .
Nevinocho