I can't see how you can increase the contrast ( with a fixed light source colour/grade ) from a contact print situation, by going to any form of enlargement. Contact printing pretty much has the maximum directionality of the light reaching the negative - because it is illuminated by a small distant lens pupil that might be 2 or 3 feet above the neg.
There is a thread here in the UK where I showed how i worked through my thoughts on this.
This is where I joined, but I was late to the party -
http://www.film-and-darkroom-user.or...t=14020&page=6
There are print scans near the end.
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