@Tombo Thank you for reaching out!
The Co-op Cycles ADV 4.2 is not a model being carried over in 2021. Depending on what kind of riding you are looking to do, you could look at the Salsa Blackborow, which is a fat-tire cargo bike that can run varying sized tires from 26" x 4", to 27.5" x 3.25", to 29" x 3". Another option would be to add a Jones bar and a rear rack to a Co-op Cycles DRT 2.2, which has the same frame and tire size as the ADV 4.2. The Co-op Cycles ADV 4.2 was a niche bike build and, unfortunately, there aren't a lot of other similar options on the market for a cargo-hauling-plus-sized-tire-mountain-bike.
Hopefully this helps, thanks!