In the immediate aspect of this case Democrats actually have a lot more to gain since they have so many more large states that vote heavily in their favor. States like California, New York, New Jersey, and Maryland all would be empowered to draw extreme D gerrymanders without any oversight.
Republicans are limited because all their large states vote more 50/50 like Georgia, Florida, Texas, and Arizona. There's only so much gerrymandering they can do when the votes simply aren't all there.
Will Democrats be willing to aggressively gerrymander though? Or will they yet again chicken out in the name of "bipartisanship"?