You want to send an email with an image in the body, for example with the Office 365 Outlook: Send an email (V2) action.
In the body, first switch to code view by clicking '</>' (or for some actions, set IsHtml:Yes) see note. You can use HTML to embed the image, to do so add the following to the email body where you want the image to show:
<img src="URL" />
URL is a link to the image, this can be a public link or dynamic content from a previous action (such as a link for an image in sharepoint)
URL can instead be a base64 encoded image, you can find a tool/website online that will encode for you (or use the 'dataUri()' expression with file content from a previous action)
You can specify additional attributes such as to: configure the size of the image or alt. text in case the image cannot load. See resources below for more information
Example image with a link and size:
<img src="https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTf8peeAQ8Jbw4lowjdYM9OYVJFJr8EwgGNTsJ6BtbqPdNHWz2m" width="500" height="100">
Example image with base64 (clipped for readability) and the 'alt' attribute:
<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAHMAAABzCAMAAA......" alt="SomeImage" />
NOTE: To see if your action supports HTML, check if the action has the parameter `body` of type `html` in the connector documentation. Otherwise, for some actions you may need to choose `Is HTML: Yes` under 'Advanced Options'
Additional ways to configure <img>: Image Embed element reference