Backpacks for training are made in a similar style: these are roomy bags with two straps, which have 1-2 main compartments with pockets on the sides for small things. Their main difference from everyday or fashion models is a more thought-out structure of compartments, increased capacity with space for things, shoes and various accessories.
The outer layer - usually polyester or a similar synthetic fiber - will provide protection from dirt, light rain and dust, while the back can be ventilated to prevent perspiration. The straps are made with soft pads to reduce pressure on the shoulders. https://alternative-me.com/how-to-choose-a-beach-bag/
The job of these models is to bring your uniform, shoes and a few more accessories to and from workout. However, nothing prevents you from using them as everyday options - since the capacity allows, and the colors are for every taste!