The word "boss" literally means "a person who exercises control or authority", but how do we often interpret it? Does the word itself give them control or authority? For example, in the case of a colleague getting promoted to be the boss. Does she or he now have control or authority over your work? Perhaps, if you view her as capable. If you don't, there's angst.
What mental model do we apply to a boss? Some people like being told what to do. Others prefer a facilitator. And others only require rare oversight. The control or authority we attribute to a boss is the control that she or he has over us.
What if you are the one that gets promoted to being the boss? Knowing how others perceive you matters. You can set the tone, but not everyone is listening to it from the same frame of mind.