If we are talking Visual Studio Code nowadays you set a default formatter in your settings.json:

  // Defines a default formatter which takes precedence over all other formatter settings. 
  // Must be the identifier of an extension contributing a formatter.
  "editor.defaultFormatter": null,

Point to the identifier of any installed extension, i.e.

"editor.defaultFormatter": "esbenp.prettier-vscode"

You can also do so format-specific:

"[html]": {
    "editor.defaultFormatter": "esbenp.prettier-vscode"
},
"[scss]": {
    "editor.defaultFormatter": "esbenp.prettier-vscode"
},
"[sass]": {
    "editor.defaultFormatter": "michelemelluso.code-beautifier"
},

Also see here.

You could also assign other keys for different formatters in your keyboard shortcuts (keybindings.json). By default, it reads:

{
  "key": "shift+alt+f",
  "command": "editor.action.formatDocument",
  "when": "editorHasDocumentFormattingProvider && editorHasDocumentFormattingProvider && editorTextFocus && !editorReadonly"
}

Lastly, if you decide to use the Prettier plugin and prettier.rc, and you want for example different indentation for html, scss, json...

{
    "semi": true,
    "singleQuote": false,
    "trailingComma": "none",
    "useTabs": false,

    "overrides": [
        {
            "files": "*.component.html",
            "options": {
                "parser": "angular",
                "tabWidth": 4
            }
        },
        {
            "files": "*.scss",
            "options": {
                "parser": "scss",
                "tabWidth": 2
            }
        },
        {
            "files": ["*.json", ".prettierrc"],
            "options": {
                "parser": "json",
                "tabWidth": 4
            }
        }
    ]
}