https://wccftech.com/apple-now-offers-an-amd-radeon-pro-w5500x-for-mac-pro/

Apple has started offering a new AMD Radeon Pro W5500X MPX Module for Mac Pro. The graphics card is an upgrade from the Radeon Pro 580X, which ships with 8GB GDDR5 memory, while thee W5500X ships with 8GB GDDR6 memory.

The upgrade is available during the build-to-order process for Mac Pro, and costs and additional $200 over the base model Radeon Pro 580X. It is also available as a standalone purchase for $600, which can be used to upgrade an existing 2019 Mac Pro.