How to enable Azure Arc command line
Microsoft has offered Azure Arc to manage your Windows and Linux machines hosted outside of Azure, on your corporate network, or other cloud provider consistent with how you manage native Azure virtual machines. Its command lines have been released recently. Please note it's still under preview at 12/6/2020.
Command lines for Azure Arc has not been included into Azure Cli yet, so you need to execute commands below.
az extension add --name connectedmachine
It takes about 30sec, like below, and you can try the commands right after that.