Depends which Roubaix you have. The disk version Roubaix will likely accommodate 32mm wide tires...is a completely different frameset with 135mm drop outs, different front fork...shorter head tube due to higher fork crown to axle dimension etc. If buying new and wanting 32mm tire clearance, I would contact Specialized and ask them.

Btw, I have a different view of what I like in a gravel bike. I prefer a carbon 29er with flatbar because I prefer the leverage of a wider handlebar for control and a slightly wider tire that will fit on a 29er. I have ridden a fair amount on gravel and that is my vote.