Certain lightbox scripts have this option (e.g. Fancybox3 or Lightgallery). You can set it through Photonic → Settings → Lightboxes. There should be options to disable right-clicks.
This is, however, an illusory measure. It is very easy to get around the inability to right-click and get the photos, because, to show the photos, the user’s browser has to download it first. There is no way to prevent the user from getting the photos unless you watermark them at the source.