Thanks, @Pstork1 for answering. By "in response using a Flow" I meant using HTTP Response. Following is what I have done.

Note that the users use another web application, wherein the web UI of that application, they click a button, that sends an HTTP POST request, which triggers this flow. I intend to send the word doc in the HTTP response to that request. I am assuming that since I am using the Content-Disposition header of type attachment when the application receives the word doc in response, the browser will open the doc automatically (provided the application is invoking POST request from the front-end).
Now I am testing this HTTP post response using the "Send and Download" option in Postman, whereby I see the word file being downloaded. But I get the following error

Please note that the file opens correctly when sent as part of the email as an attachment.