to be pushed or acclaimed into a position of leadership or responsibility by others, often unexpectedly

他本不想担任工会主席，但在大家的极力推荐下，也只能黄袍加身了。

expression · to be proclaimed emperor, historically referring to the act of being draped in a yellow robe by supporters to signify taking the crown

赵匡胤在陈桥兵变中黄袍加身，结束了五代十国的混乱局面。