What Do I Do?
No matter the role, designer start with concept work for it. Concept design can range from the entirety of a packaging design or product to something like graphic work for an already established template or brand.
Perhaps the product doesn't yet have an established brand. The designer would conceive of the product's packaging as integral to the overall brand, creating logos, style guides, packaging concepts, and more in line with the vision of the product or client.
All of the graphic work involved with packaging design. Logos, layout, illustration, typography, and more. Designer may have to contribute to any of those or even all of those facets of the design process.
Packaging Template Design:
This one requires some industrial design know-how. Designing the template itself means knowing how an object or product's packaging (box, label, bag, display, etc.) needs to function in the real world and how to it needs to be manufactured.