Is the trustee sinful if his manager asks him to pay money as a bribe to others, or asks him to take this money for himself?

Bribery is forbidden and is one of the major sins. The Messenger of Allah, peace and blessings be upon him, cursed the one who gives and the one who takes a bribe. The matter becomes worse if the bribe leads to something forbidden. It is not permissible to obey the manager and cooperate with him in bribery, for Allah Almighty says: "And do not cooperate in sin and aggression," and the Prophet, peace and blessings be upon him, said: "There is no obedience to a human being in disobedience to Allah." You must advise him and remind him of Allah. If he does not respond, then refer his matter to higher authorities.