By default, the presentation of excerpts of posts in the Divi blog module are disabled.

If you wish to show excerpts in the blog module on a specific page, open that page’s settings, navigate to the Custom CSS section, and add the following code:
.lagoon-blog .post-content p {
display: block !important;
margin-top: 5vh;
}
If you wish to apply this to all blog modules on your site, add the same code to either the Custom CSS section in the Divi Theme Options panel, or to the theme’s style.css file, located in the wp-content > themes > lagoon folder on your server.