How to upgrade the 27-inch 5K iMac (2019) with a massive 128GB of RAM [Video] - 9to5Mac
32GB NEMIX RAM Memory for 2019 Apple iMac 27 inch Retina 5K (iMac19,1 A2115), 2018 Apple Mac Mini (Macmini8,1 A1993) System Specific Memory - Newegg.com
The 27-inch iMac 2019's RAM may be upgraded to 128GB - NotebookCheck.net News
Apple iMac 5K 27-inch (Mid 2019) 3.6GHz i9 16GB RAM 512GB SSD - Buy Refurbished iMac 2019 at Techable