How to Autocomplete tag.className in Visual Studio Code

By using the Ctrl + , (comma), it’ll open the setting panel of your Visual Studio Code. Click on “Emmet” from the left side and keep the following options checked (true):

If you are using the latest version of Visual Code. Keep the checkmark for the followings:
Emmet: Show Suggestions As Snippets
Emmet: Trigger Expansion On Tab