I am not familiar with Joseph Parker, but it looks like he did great in his last three fights. But despite that, I don't think he'll be able to beat Usyk. In Usyk's rematch with Dubois this July 19, he showed how dominant he can be in his fight. I have no doubt Usyk will outbox Joseph if they fought.
Too bad Parker didn't get to fight Dubois, it would have been interesting to watch.