You cannot explicitly set the height of the check button. The height will be decided by finding the height needed to show the content and then adding on the padding. So if you want the check button to be bigger you need to either add bigger content (increase font size, larger images) or increase the padding.
To change the padding around the content use...
StateCommon -> CheckButton -> Content -> Padding
If you run the Navigator Playground sample that can be started from the Krypton Explorer then you can play around with the padding and see the results straight away to see what I mean.
Hope that helps.