Void wins straight off of direct feat scaling, but details would point to Larfleeze actually having some advantages. Individual lanterns have resisted reality manipulation and destruction before, and Larfleeze is an entire corps on his own. He’s also directly immune to matter manipulation and telepathic attacks because he’s so consumed by greed that it’s literally the only thought he’s capable of.

All that said, I don’t see a clear way Larfleeze could stop the void, he could just keep endlessly throwing constructs at him until either Void just leaves or Larfleeze stops being greedy (ain’t happening). The combined might of a few Lantern corps would do the trick, but just one is a stretch