Do games even have separate assets for different graphics settings? I've always assumed they just scale them up/down based on the options that you choose, so there's no way to not download the higher resolution ones, since they're technically the same ones anyway.
For the most part probably not, but they most certainly could. That said, I think games use e.g. different models at different distances (you don't need as many details for distant objects), but I don't think models take up enough space to warrant using different models for different graphical settings. But for e.g. textures I don't see why there couldn't be different assets for different settings. It's more about whether you'd want it (see Pemalite's post).