How do I scale an instance to precise dimensions?

I have a master component that is 1440x811 which consists of photos and text, and is made using auto layout. Constraints are set to Hug contents vertically and horizontally. I want to make smaller versions of it as variants - 600 wide, 250 wide, and 150 wide. I want to be able to update the text and replace photos on the 1440px wide master component and then have the smaller variants update automatically.

I thought the best way to do this would be to create instances of the 1440px wide master component, scale them down, and them make them components. Then combine all of them as variants. However I can’t figure out a way to scale down the instances. If I use the Scale tool, I have to rely on dragging it and can’t get the exact dimensions I need that way. If I change it from Hug Contents to Fixed Width and Height, then enter new dimensions, the content overflows instead of scaling proportionally. If I frame the instance, same issue. What is the proper way to do this?