Thank you for the opportunity to help you with your question!
As a first step, I will have a one to one discussion with the manager. In that discussion, I will try to explain him the negative impacts of his behavior and will end the discussion by giving him a warning in a very subtle way. If his coercive ways still continues, I will correct him by telling him not to act in this way in front of his sub-ordinates.
Please let me know if you need any clarification. I'm always happy to answer your questions. Kindly best this answer if it has helped you.