How to use colors from colorScheme in component level themeing

[kumarragMSFT]

I am using react-northstar and I want to set the background color of a Box to colorScheme.brand.background3 but unlike the example given here I want to set this at the component level and not as a theme. Is there a way to do this using the variables prop in the component? There is no documentation on how the colorScheme api can be used for individual components.