Adding Tags to Existing Language

Can you add Lezer tags for text/keywords in an existing language?

I’ve tried using styleTags but it doesn’t seem to recognize just any text. Is it limited to what’s already registered in the language grammar/parser?

const customizedJavaScriptLanguage = javascriptLanguage.configure({
  dialect: 'jsx',
  props: [
      'xyz': tags.keyword

You can add tags for existing syntax nodes yes, but tags are derived from the parse tree so if something isn’t in there you can’t tag it.

Thanks for clarifying. I suppose a StateField with Mark Decorations would be a better approach.