Display such as "Viewable only by logged-in users"

I had been browsing the gallery while always logged in, so I didn’t notice, but when not logged in, the images you can view are limited. Is there a setting for this? If there is such a setting, I would appreciate it if you could add a notation like "Viewable only by logged-in users," similar to the "R15" indication, to help me decide whether to generate and publish images.