default_setting_overrides.json

{
  "@jupyterlab/docmanager-extension:plugin": {
    "defaultViewers": {
      "markdown": "Jupytext Notebook",
      "myst": "Jupytext Notebook",
      "r-markdown": "Jupytext Notebook",
      "quarto": "Jupytext Notebook",
      "julia": "Jupytext Notebook",
      "python": "Jupytext Notebook",
      "r": "Jupytext Notebook"
    }
  }
}