Not only do Orcas not "fight" great whites, but they have learned how to use tonic immobility[1] to get sharks (and sting rays[3]) into a state of complete paralysis before the rest of the pod rips them to shreds and they all feast on the shark. Sharks have one trick against the Orcas, and that is they can dive much much deeper than the whales, and stay under forever. However, a pod of Orcas will force a shark to stay near the surface to tire him out before flipping him upside down to snack on[2].
[1] https://www.sharktrust.org/tonic-immobility
[2] https://allthatsinteresting.com/killer-whales-eat-sharks
[3] https://www.earthtouchnews.com/oceans/whales-and-dolphins/wa...