Each yarn package will have a recommended crochet hook size to be used with it, depending on the yarn weight. Yarn weight has very little to do with the actual weight (heaviness), it is more to do with the thickness of a yarn strand. Most yarn manufacturers use a common standard of numbering the yarn weight so that a crocheter or knitter can easily substitute the yarn whenever needed.
https://www.knitpro.eu/blog/what-crochet-hook-to-use-with-what-yarn/en