SiteScripts/DefaultBranding.json

{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/site-design-script-actions.schema.json",
  "actions": [
    {
      "verb": "setSiteBranding",
      "navigationLayout": "Cascade",
      "headerLayout": "Standard",
      "headerBackground": "None",
      "showFooter": false
    }
  ]
}