X-plane 11 has a growing number of detailed airports. It is based on how many users are contributing to improving them all over the world. All this is centralised on what's called the Scenery gateway :
Moreover, there are many many airports creted by even more users on different websites, where you can find them for free :
XPFR.org ... And many other websites.
These airports use customised objects, not created by laminar. Sometimes, these objects are included in the package when you download them, and sometimes you need to install additional libraries of objects so that many different airports can share the same custom objects.
The number of airports is huge.
And of course, some editors sell airports, usually with a better quality. But you can have a great number of great airports for free. And many other additional products like aircraft, plugins, textures etc...