I know that some graphic designers use ready-made mockups for printing products. Where can I find these for free?

If you are looking for free mockups for graphic design, then I know that you can find them on special portals, for example, here https://www.ls.graphics/free-mockups/box-packaging I found mockup for a packing box and was able to make a cool birthday present for my daughter. I used this mockup as a template and added my design to this box. When I printed this, I realized that I can make real packaging for my gift. It was very cool and I'm grateful to the designers who added this mockup to the site, because I'm not so good at graphic design to create mockup boxes in expanded form and not be mistaken in size.