I've not read this about RAM. Please share your resource for this info.
https://www.androidcentral.com/ram-what-it-how-its-used-and-why-you-shouldnt-care
It's toward the beginning; after the section of how your phone uses RAM. To a degree, this is more of a topic on why clearing RAM/task killers are counterproductive, but the adage of unused RAM is wasted stuck out in my mind here.
Assume for a moment the rumor of 10 or 12 GB of RAM on the S10, I view this as like buying an Audi R8 just to run down the block to pick up milk. What is needed for the OS, versus what is used, and what the phone comes with all should come into play in a buying decision.
Another source: https://developer.android.com/topic/performance/memory-overview
'For example, when a user first launches an app, a process is created for it; but when the user leaves the app, that process does not quit. The system keeps the process cached. If the user later returns to the app, the system reuses the process, thereby making the app switching faster.'
That indicates that the RAM is intended to be kept loaded in memory until it is needed later or deemed by the OS to be terminated.