Family coverage is governed by the official program terms, which should be read directly for who is included, whether additional gifts or fees apply and what status family members receive. General rules about spouses and unmarried children under 21 apply only to the extent the official framework adopts them.
Check the family terms on the official page before assuming anything
For most categories on this site the family rules are settled: a spouse and unmarried children under 21 accompany the principal, and their work rights depend on the category. For the Gold Card, the family terms are whatever the official program page and FAQ state, and Yusuf should read them for three specific points — whether each family member requires a separate gift or fee, whether children are subject to the usual under-21 and unmarried limits, and what status a spouse receives and when. He should also consider the ordinary facts that any family case turns on: each family member's citizenship, any child within two years of 21, and whether his wife's own career would be better served by a category that gives her employment authorization in her own right.
Hypothetical example: Otto expects his spouse and an unmarried twenty-year-old stepchild to relocate with him under the Gold Card process. Before any payment, he should read the current government terms line by line and make a chart of each person's relationship evidence, age position and required payment or filing. Marriage, birth and adoption records settle the relationships; assumptions borrowed from another category do not.
He must also confirm whether an applicant-made payment to the U.S. government is required for each person. This program is not a conventional visa category, so family benefits must be taken from its current official terms and the underlying legal route.