96GB Memory Upgrade Kit for 2019-2020 Apple iMac (27-Inch)
The 27-inch iMac 2019's RAM may be upgraded to 128GB - NotebookCheck.net News
OWC 16.0GB 2x 8GB DDR4 PC4-21300 2666MHz SO-DIMM 260 Pin Memory Upgrade Kit For 2019 iMac and 2018 Mac mini Models and PCs Which Utilize PC4-21300 SO-DIMM. Model OWC2666DDR4S16P - Newegg.com
OWC has prepared RAM upgrades for the 27-inch 2019 iMac already - NotebookCheck.net News
Memory Upgrades for 2019-2020 iMac 27-Inch - Up to 128GB