I don't know of anywhere that lists all the spoke sizes ever used anywhere, or all the numbering systems, though there could be one.
However, the spoke size to use depends on the rim used. You use a spoke size appropriate for the rim (and hub) that you are using, which you choose based on the application and the tire type/size you want to use.
Some, probably many, OEM hubmotor wheelbuilders (and especially the "chinese" wheels, sometimes even of regular non motor wheels) ignore this and use thick spokes on rims that can't handle the tension required, probably because the people that buy them think thicker is better (which is only true if the rim is capable of handling it, designed for it, and the hub is too, *and* the application needs that heavy a wheel). (the companies themselves probably know better, but they might not). So you can't necessarily judge how thick a spoke is needed by the companies that produce such wheels and/or vehicles.
Too thick a spoke for a rim will require tension so high that the rim will deform or even crack around the nipple hole, loosening the spoke and letting it go slack, which means the rim flexes more and the spokes move around and can break at the J-bend at the spoke flange. What the specific failure mode causing it is, I don't know, but it is what I see with wheels built this way, vs wheels built with spokes thin enough for the rim to handle the tension of.
So....what are you wanting to build that needs new wheels?