How much of RAM is actually full vs just cached stuff that can be purged when memory pressure increases? Just because Windows task manager says 10 GB RAM are u

How much of RAM is actually full vs just cached stuff that can be purged when memory pressure increases? Just because Windows task manager says 10 GB RAM are used doesn’t mean it could easily do with half of it, just foregoing a bit of preloading of apps/files that you might perhaps be using.