Women need to change what they are doing that undermines their authority
It is not just the power stance, though that is a good way to stand when talking to others at work.
Stand up when someone comes into your office. It serves 2 purposes. First it will keep the other person from acting like you have all the time in the world to listen to them. Second, they are not looking down at you.
Train yourself not to end your statements as a question. There are two ways women do this that undermines their authority. First they end with OK? or right? or some time of question that means you are asking if what you said is ok with them. Second, even if you don’t make it an obvious question, you use the question tone of voice at the end of you sentence. You might want to record yourself and listen.
Back to the power stance, feet separated about a foot or foot and a half, facing the other person directly. Don’t cross your legs or lean on anything. Look directly at them. Make eye contact.
BTW, this is true for men, too. It just is observed more often in women.