We originally incorporated the Colorbox lightbox feature for viewing images from the WordPress Gallery Shortcode (even the block gallery). You can view your photos in a popup overlay viewer.

NOTE: We are planning to remove the lightbox in the next update because it does not work with actual image captions correctly (not compatible). We will be offering an alternative.

  • Go to Appearance > Customize > Other Options
  • Look for the Enable Gallery Lightbox setting and toggle the setting
  • Click the Publish button
screenshot to enabled the lightbox by Colorbox

UPDATE: Because the Colorbox gallery script is now gone, the alternative is to check out a free plugin called WP Featherlight. This works with the block gallery. Of course, you also have the option to use other gallery plugins if you need something more robust.