If I override the extension supported by the plugin, then the formatting ignores the files supported by the plugin, which is confusing.

Usually plugins only support one or two extensions, but prettier supports dozens of file extensions, so if I want to add a new file extension to prettier I have to manually type in all the extensions supported by prettier.

{
  "prettier": {
    "associations": [/** all prettier support file extension glob */, "**/*.new_html_extension"],
    "new_html_extension.parser": "html"
  }
}