Sisters pushing each other’s buttons

Hello Nicoleen,
I learned so much from you! Thank you very much for your help and support in my parenting journey!

I have a seven and nine years old. They are girls. The oldest likes to talk and express herself and be in charge. Sometimes, she would order the younger one what to do and how to do things. She has a rich vocabulary and is very convincing when expressing her thoughts and ideas.
When she power struggles with her sister, she raises her voice and express madness to get her way.

The younger one doesn’t like to argue with the older one because she is timid and quiet and tends to run away when the older one is loud or out of control.
When they argue, usually the older one gets mad, and the younger one either goes away crying, having hurt feelings, or turns her back and leaves with a sassy smile, “looking down” at her sister and showing superiority for not losing her cool.
Please help me break this pattern.

Thank you very much!