It is stated in this post:
That a multiple variations feature may become available in version 3.0. Someone answered my comment stating that it was already available, but it doesn't have the robust variation options that other eCommerce platforms have. This is a "single variations" option, not a "multiple variations" option. Meaning that you can add "Red", "Green", "Blue", etc varations, but not two dropdown menus where one is 12 different colors and another is 7 different sizes.
Is a feature like this still planned?