Ms. Peoples Wagner, 30, will rejoin the publication after a two-year stint as the top editor of Teen Vogue, where she was the youngest editor in chief of a Condé Nast magazine and one of the few Black journalists to have led one of the company’s publications. She was previously a fashion market editor for The Cut, which started out as a fashion blog on the New York Magazine website and became a stand-alone site in 2012.