How to Upgrade/Replace the Memory in a 21.5-inch iMac (2019) iMac19,2 - YouTube
Amazon.com: 2019 Apple iMac with Retina 4K Display (21.5-inch, 8GB RAM, 1TB Storage) (Renewed) : Electronics
Adamanta 64GB (2x32GB) Memory Upgrade for 2020 Apple iMac 27" w/Retina 5K Display, 2019 Apple iMac 27" w/Retina 5K Display, 2018 Apple Mac Mini DDR4 2666Mhz PC4-21300 SODIMM 2Rx8 CL19 1.2v DRAM
Can you upgrade the RAM in the 27-inch iMac? | iMore
Memory Upgrades for 2019-2020 iMac 27-Inch - Up to 128GB
Install memory in an iMac - Apple Support
How to upgrade the RAM on the 27-Inch iMac (2020) | AppleInsider