How can I specify an open or schema extension to be included on the sign-in user query so I can get back additional user settings without having to make another user query?

Question

How can I specify an extension (open or schema) to add to the user query that the sign-in process makes so that I don't have to immediately make a separate subsequent user query post sign-in? It seems wasteful to have to do so. (time/bandwidth/power/etc.)