If you need a dynamic size component, you may want to explore different technique. Once the instance is set there is no way to change it is size. The only exception is for hug content components though. Which means if your “Square” sizing is set to hug contents and it is size determined by its content, than you can have truly dynamic size
Try this - https://www.figma.com/file/eKsQvUUMNjmAaEDw57Xrk4/Debug-(Copy)-(Copy)?node-id=201%3A152