The available ESXCLI commands depend on the ESXi host version.
When you run an ESXCLI command, you must know the commands supported on the target host. For example, if you run commands against ESXi 7.x hosts, ESXCLI 7.x commands are supported. If you run commands against ESXi 6.x hosts, ESXCLI 6.x commands are supported.
Some commands or command outputs are determined by the host type. In addition, VMware partners might develop custom ESXCLI commands that you can run on hosts where the partner VIB has been installed.
Run esxcli --server <target> --help
for a list of namespaces supported on the target. You can drill down into the namespaces for additional help.