pose as someone
phrasal verb with pose verb uk/pəʊz/ us/poʊz/
C2 假扮（某人），装成（某人）
If you pose as a particular person, you pretend to be that person in order to deceive people.
He's posing as her date, but he's really her bodyguard. 他扮作她的约会对象，但实际上是她的保镖。