As I understood your problem is that you want to control how much the image will be increased in each different screen size. You can control everything. What you need to do is to assign an equals width constraint on your image. Preferable on image's width. The relation will be with the superview and then you can change the relation by adding your own Multiplier.
What you need to do exactly:
1) Select your image view.
2) Hold down the control key. While you are holding it, drag your mouse from the image view to the outer view.
3) Select 'Equals width'.
4) Double click on your constraint in the 'Constraints' tab.
5) Ensure that the image view is presented as the first item, if not click on the first item and select 'Reverse first and second item'.
6) Play with the multiplier until you are satisfied with the result on the preview screen.
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