The 27-inch iMac 2019's RAM may be upgraded to 128GB - NotebookCheck.net News
How To Upgrade Ram on a 27" iMac | 2020, 2019 iMac Ram Upgrade - YouTube
NEMIX RAM Compatible for 128GB (4x32GB) DDR4 2666MHz PC4-21300 SODIMM Memory Upgrade for Apple iMac Mid 2020 (iMac 20,1/20,2) / Mid 2019 (iMac19,1) 27-inch w/Retina 5K, Late 2018 Mac Mini 8,1 at Amazon.com
How to upgrade the RAM on the 27-Inch iMac (2020) | AppleInsider
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
OWC Enables Up to 4x RAM in 2019 27" iMac 5K vs. Highest Factory Options
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
Amazon.com: v-Color 128GB(4x32GB) 2666MHz ddr4 Compatible for iMac Retina 5K, 27-inch, 2019 and iMac Retina 5K, 27-inch, 2020 Non ecc SODIMM Mac Memory Ram Upgrade pc4-21300 CL19 260-pin 1.2V(TN416G26S819Q-VC) : Everything Else