JavaScript Design Patterns – Name for Function Returning Function Pattern

What you are doing is called a fluent interface.

From Fowler's article:

In essence we create the various objects and wire them up together. If we can't set up everything in the constructor, then we need to make temporary variables to help us complete the wiring - this is particularly the case where you're adding items into collections.

Which is where @Frank was talking about "Phantom Types". Also Fowler says

Probably the most important thing to notice about this style is that the intent is to do something along the lines of an internal DomainSpecificLanguage. Indeed this is why we chose the term 'fluent' to describe it, in many ways the two terms are synonyms. The API is primarily designed to be readable and to flow.

The way I have seen this discussed is to use "fluent" as an adjective, so in your case it would be a "fluent builder".

That is an OOP Data Descriptor. Although you are describing additional information about a class rather than information about bits in memory, the fundamental parity still applies; you're describing in one place useful aspects about data in another place.

I'd advise you to adopt that name, write up a clearer definition of the pattern, and use the name in code. ("Type" already means something in PHP, so you really shouldn't use it.) So, your user class could be changed as follows:

class User {
   ...
   public function getDescriptor() {
   }
}

class UserDescriptor {
   ...
}