https://wccftech.com/mac-pro-apple-silicon-specs/

For the time being, we know that the Mac Pro will reportedly be around half the size of Apple’s current Intel-powered workstation, most probably because its internals will not need massive levels of cooling to keep temperatures under check, including the custom chip. In fact, Apple may go into fifth gear when it comes to developing this SoC because one report states that the Mac Pro could be configured with up to a 40-core CPU and 128-core GPU.

Apple could have little concern about the Mac Pro’s ability to cool a powerful chipset thanks to its adequate size, and Bloomberg reporter Mark Gurman believes that the custom chipset will be based on the M1 Pro and M1 Max powering the 2021 MacBook Pro lineup. However, having a 40-core CPU and 128-core GPU can either mean that Apple will be developing a massive die or have multiple dies on the Mac Pro’s logic board.