Not sure, it could be allocated in the firmware, kind of like integrated GPUs on desktop/laptop processors. For example my Amd 6800HS laptop with 16GB RAM has only 14 available because the GPU takes up 2GB (but I can change it in BIOS)

The huge amount of RAM on Android in general is less about supporting a single hungry app and more about keeping as many apps as possible in memory so that you can multitask between them without any of them losing their state. If one app manages to eat most of the memory, then it’s already too little for the intended experience.

Also the memory is supposed to be enough for at least the 7 years this phone will be supported for - that’s plenty of time for apps memory footprint to grow.

Maybe I’m biased by always having used devices with RAM size in the lower end (which is always also coupled by a not-so-great CPU so when you do run out of memory and the system starts killing apps you want to multitask between, you’re going to notice it that much more), but I’ll always take more RAM in a device that might survive a decade with a couple of battery swaps.