The following is an ESXi 6.7 U3 host with 1.5 TB of memory. Notice the kernel values remains constant over a long period. The number of running VM eventually dropped to 0. While the Granted counter drops to 1.5 GB (not sure what it is since there is no running VM), the kernel did not drop. This makes sense as they are reservation and not the actual usage.

Based on a sample of 500+ ESXi hosts, the range varies from 6 GB to 88 GB. In an ultra large ESXi with 12 TB RAM running vSAN and NSX, the reservation went up to 300 GB.

Utilization vs Reservation

Logically, utilization does not always correspond to the reserved amount. The following chart shows the reservation remains steady when the utilization drops by 90%, from 40 GB to single digit.

To see the actual usage, choose the metric Resource Memory Consumed metric from vSphere Client. Stack them, and you see something like this. The system part typically dwarfs the other 2 resources.