If I understand correctly, Intel doesn’t build the wifi directly into the processor, but they have some of the hardware inside the processor that will interface with a secondary Intel wifi component.
So the manufacturers can use the Intel wifi with very little footprint (and cost?) overhead, or deploy their own wifi.
Apple has typically done stellar deployments of wifi. There are some wifi 6 deployments out there that would perform worse (in throughput capacity) than some Apple MacBooks from the 2013 era. It’s not consistent across all models, but if Apple wants to go with a three antenna system again then I don’t think they can do that based on the current Intel tech. That could change of course.
So even if the processor supports wifi 6, it’s not certain that Apple will use it. Though they probably will. Certainly it’s not quite true to say that Wifi 6 will always be a better choice than Wifi 5. And just like not all Wifi 5 deployments are equal, neither are all Wifi 6 deployments.