Recipe using docxtemplater to generate docx reports
npm install @jsreport/jsreport-docxtemplater

See general documentation for office preview in studio here.
{
  "template": {
    "recipe": "docxtemplater",
    "engine": "handlebars",
    "docxtemplater": {
       "templateAssetShortid": "xxxx"
    }
  },
  "data": {}
}
In case you don't have the office template stored as an asset you can send it directly in the API call.
{
  "template": {
    "recipe": "docxtemplater",
    "engine": "handlebars",
    "docxtemplater": {
       "templateAsset": {
          "content": "base64 encoded word file",
          "encoding": "base64"
       }
    }
  },
  "data": {}
}