An enlarged neg will not have the appearance of less grain unless the duping material itself has substantial grain. here's the reason: the grain in the original neg will be magnified in the process of going to the interpositive, and that grain will dominate the grain of a fine-grained duping film. So, for example, if you use tmax100 as your duping film, then the grain from the source neg will dominate... tmax is essentially grainless when contact printed.
But, I think that if the duping material has ample grain itself (e.g.a traditional grain film), then that grain may control and sort of subdivide the grain from the original neg. So then it might give the appearance of reduced grain.