I may be misunderstanding your question, but as stated it: "No".
The Data Extract API has no capability to connect to a database and explore the database's schema -- that's your job as the programmer -- using whatever mechanism you want to leverage. All the Tableau Extract API does it create the schema (an empty Tableau data extract) that you tell it to create and then populate the table in question with rows that you provide.
No. You are in charge of your data