I have an autolaunched flow that I'm invoking with a rest api call. Here's the sample code that shows how I call my flow from a express.js server.

var _request = {
  url: '/services/data/v54.0/actions/custom/flow/FlowName',
  method: 'post',
  body: JSON.stringify(
    {
      inputs: [
        param1: value1,
        param2: value2,
      ]
    }
  ),
  headers : {
          "Content-Type" : "application/json"
      }
};


const salesforce = config.getProperty('SalesforceRest');
const conn = new sf.Connection({ loginUrl: salesforce.host });

try {
  await conn.login(salesforce.userName, salesforce.Password + salesforce.Token);
} catch (error) {
  return res.status(500).send(errorResponse.ServerError(`Salesforce login failure: ${error}`));
}

conn.request(_request, function(err, resp) {
  console.log(resp);
});

I'd like to know how to set the statusCode and the response message values in my flow. For example to return a statusCode = 400 and message = 'Missing required value' when my flow runs and finds out there's a missing required value. I tried to be clear with my question but please let me know if I need to put more information here.