Scrivener doesn’t care whether a document has sub-documents or not.
A specific Compile format might care. For instance, if the format assumes that the folder document contains no text, and that the actual content is contained in one or more text sub-documents.
But you can always assign whatever Section Types and Section Layouts you think are appropriate, completely independent of the Binder structure. That’s the whole point of the Scrivener 3 approach to the Compile command: you don’t have to force your Binder outline and your output document to match.
Section 7.6 in the manual discusses Section Types in more detail; Section 23.3.3 explains how to assign Section Layouts.