You would first need to extract the image attachment URLs into a separate field. You can use this automation to achieve that. Then you would pass that direct URL in an HTML image tag.
Example (where URL is the name of the field used to store the attachment's public URL):
<img src="{URL}" >Please note that this tag can only handle a single image, i.e. multiple comma-separated URLs in a single field are not supported. To include several attachments you'd need to split up the different URLs in different fields and then create individual <img> tags for each of them.