OWC Can Upgrade the iMac Pro to 256GB
The iMac Pro ships with 32GB (or whatever was purchased), but iMac Pro users are not stuck with the memory configuration when purchased:
Along with up to 128TB in the 2019 iMac 5K, the iMac Pro can be upgraded to 256GB (or 64GB or 128GB) via OWC’s turnkey install.
MPG strongly recommends the OWC Memory + Pro Install option as installing memory in the iMac Pro is a complex process that requires a skilled technician.