As it’s theme dependent, what theme are you using? Where do you want excerpts with read more? Where do you want full content? (besides single post view, if anywhere else)

If the theme uses the_content() for list pages, the author can control how much is shown by putting <!--more--> tags in the content. The function will display up to the first more tag (or all if there are none).

If the theme uses the_excerpt() for list pages, the author can control how much is shown by writing a manual excerpt. The function will display the manual excerpt as is, or generate one (strips all HTML tags from the content and take the first 55 words) if there isn’t one. Themes can also give an option of how many words to use in the generated excerpt.

The thing is that it’s not always possible for a theme’s design to support both options. For example, if the theme author has designed a theme where the posts are laid out in a grid, it would never look good to display the full post, so they use the excerpt, while other themes, like Twenty Seventeen, are specifically designed to display the full post content.

Decide how you want to manage excerpt content. Manually in content with the <!–more–> tag, manually in the separate excerpt field, or automatically take the first 55 (number can be altered with a filter) words. Pick the appropriate function as Joy described and use it on the related templates in your child theme.

I need to know how to find the exact line where the Read More link will take the reader to so I can copy it and paste it in my Mailchimp newsletter.

I did this before but I have forgotten. Thanks so much!