Check the label. Anything with sulfuric and phosphoric acid is good for rust removal. The reason why it's in cola is simply because without it, it would be way too sweet from all the sugar.
Isn't it the opposite? Soda would be bitter AF cause of the caffeine and the carbonic acid is added to give it the fizz, then they dump a ton of high fructose corn syrup in.
The carbonic acid is for the fizz, yeah. The sulfuric and phosphoric acids are to regulate sweetness. Sodas are syrups that get diluted with water hence the need for all that sugar.