Why would Apple not be able to match an i9-10850K from the start? As I wrote before A13 Bionic in iPhone SE/11 at 2.7GHz already outperforms i9-9900K at 3.6GHz 95W in iMac 27" 2019 in single core. A12Z Bionic at 2.5GHz 7W in iPad Pro matches the performance of i5-8500 3.0GHz 6-core 65W in iMac 21.5" 2019 in multi-core. The company called Ampere has already a 80-core ARM CPU faster than Xenon 28-core in Mac Pro so there is no need for Apple to wait 2 years to launch its top AS iMac that outperforms Intel iMacs.
Apple can do a lot of things. They can build A13Z or A14Z and increase the core count, TDP, CPU speed or only use performance cores in iMac alongside better cooling. 12-core iMac is already rumored. They have lot more options to match and outperform Intel. Not to forget all the dedicated special chips they can build for different tasks and optimizing their software.