People are quoting sci-fi examples but they have been tried (and many failed) in the past. They are cities built, owned and operated by a corporation like Ford with Fordlandia in Brazil. Rent? Shops? All company-run.
Technically Disney has their own special district in Florida and have a lot of Government-like powers over it.
Sadly it was torn down once it's enclave status ceased, but if you want to see how it could have looked like from the inside Stray has a very similar atmosphere.