The female power fantasy is power without responsibility and authority without accountability - the ability to do whatever you want and not only to never face consequences, but to make other people suffer the consequences of your failures.
Topping from the bottom, basically. The power to seduce anyone, the change your appearance to suit the most powerful man in the room, to remain alluring and fertile forever.
Circe is a good example of a female power fantasy, as is
Viviane/Nimue - a woman who seduced a powerful magician, learned his secrets, and as soon as she matched him in power locked him away. She did not destroy him because she may need him later, and in any case she knows she can seduce him again so it's not like there will be any consequences if he escapes.
Note that the goal of a woman in this power fantasy isn't necessarily to destroy everyone and be a psycho: it's to gain attention from a powerful man, to provoke him into seizing you, and to use him and your children (especially your sons) to control other people whom you can't overpower. This is due to the asymmetries in male vs female reproduction: a successful woman can have at most 20 kids; a succesful man can have tens of thousands of kids. People are animals, we have powerful reproductive drives like other animals. A woman seeks success through a man, hence her skills in manipulation and provocation.
In fiction you have 3 tropes specifically for women: seductress, mother, and hag. Arguably a fourth: child. You can of course have gender neutral characterization, but no one who is politically correct today can do it well.
