Hypothetically if the House size were increased, would make gerrymandering better or worse?

[Antonio the Sixth]

Well, gerrymandering is all about degrees of freedom. On a basic level in a state with N seat you have N-1 degrees of freedom (when your state has just one at-large district, you have no freedom in drawing the lines, etc.), so gerrymandering becomes easier when you have more seats. On the opposite extreme you also end up with zero degrees of freedom when the number of seats = the number of voters, but of course no legislature ever gets to that level. Still, it's possible that there's an actual algorithmic solution that shows how degrees of freedom change with seats number, showing some type of reverse-U shape. But given how small most US legislatures are, it's almost certain that adding seats would increase gerrymandering opportunities on the whole.

Of course, this is only the abstract, big-picture view. It's almost certainly different in specific states due to quirks of political geography.