How do I add a sign on top of my elements that have hover interaction? (so users know they are interactable)

The 4 flavors of the product on my website have hover interactions set up on them so that when the user hovers over them, they can see the back of the packaging for further details. I want to add some indication on the front packaging like a plus sign on the corner that lets users know they can interact w them, (and the sign disappears when hovered on). How can I achieve this?

Here is my public share link: Webflow - Clover Snacks