You don't need any plugins to do this. Just select all lines (Ctrl ``A) and then from the menu select Edit → Line → Reindent. This will work if your file is saved with an extension that contains HTML like .html or .php.

If you do this often, you may find this key mapping useful:

{ "keys": ["ctrl+shift+r"], "command": "reindent" , "args": { "single_line": false } }

If your file is not saved (e.g. you just pasted in a snippet to a new window), you can manually set the language for indentation by selecting the menu View → Syntax → language of choice before selecting the reindent option.