Scaling objects on different points

Don't know if the title is explaining it well enough.
But I am new to XD so I could be missing something.

Basically, I am trying to dim the Background of the main page.
So I create a box, turned it into a component, and put it on the bottom of the page.
My Idea is to make it switch into a big black block when I hover over it.
But it will only scale from the top point, not the bottom.
Is there a way to move the anchor point like in after effects?

Thank you anyone who can help.

Cheer,
Ben