Not sure if there are any great resources online but there isn't that much you need to know. I'd say just download it and mess around. Here's some random tips:
Windows has its own terminal package manager called winget, it's very useful.
Nobody uses CMD anymore, everyone moved onto Powershell. The new windows terminal is also nice.
Windows has a lot of random features and controls hidden in its registry, which you can access via regedit. You usually don't want to mess around with it but sometimes it is useful.
There are a lot of scripts online to de-bloat windows and quickly default to the best privacy settings. I'd run that if you're setting up a new install. Note that some of it comes back every time you update and you'll need to run the script again.
Just understand the file system well and how to use the control panel and firewall and you'll already be ready to go as a sysadmin