Determining how to change your featured image size There are a few different ways to edit the featured image size, from PHP, to CSS, to built-in theme functions. Additionally, for more help, feel free to contact us or purchase one of our themes for additional support and more goodies! After all, this image is going to get people to take attention to the site beyond the “excerpt”. Here are a 3 different ways that you can go about changing the size of a featured image, depending on what sort of WordPress install you have. You’ll also notice that the merge tag below it is set to display the full content. MailChimp Merge Tags The last settings you’ll need to configure are the merge tags in the RSS-to-email template you’re using in MailChimp.