Question about assets

In the asset explorer, I've seen a lot of images and art and assets that seem to be fully on display them moment you view the asset. Are these preview images? Can an asset like a comic book be created with a cover image on display and have hidden content you can't see unless you are given the asset?

EDIT: I am interested, but am very new to the assets and wanted to see if it was worth investing time in to learn about for my projects.