He’ll probably try but King won’t let them. After that, it’s hard to predict how things will turn out, Marco could theoretically hold off King to allow Zoro to pass but that would mean no Zoro vs King and Zoro would fight Queen instead. Unlikely scenario in my opinion. Unless Sanji comes, stops Queen and allows Zoro to continue, then King sends Marco flying somewhere and comes back to stop Zoro.
Another possible scenario is that Sanji will stop King and Jinbe will stop Queen so Marco can take Zoro to the roof. But again, that means no Zoro vs King and I find this unlikely.
The only thing I’m sure of is that Marco won’t fight King because that’s not his place to do so, he will only clash with him at best. He already had his own journey with Whitebeard, his life as a pirate is complete and this fight isn’t his. There’s a reason he chose to stand back and doesn’t consider himself as part of the main strike force. Of course it doesn’t mean he won’t help but he’s certainly not defeating a YC or even a Tobi Roppo.