What I will share with you is how you can find the category of backlinks that are being pointed to a website along with utilizing tools like Majestic, Sem Rush or even Ahrefs.
When we're talking about effectively building backlinks for multiple different categories or niches we have to find the similarities of backlink topics that are pointing into the top performing pages. If you cannot find similarities between all of the top performing websites in each of the niches then the best next option is going to be find what are the most prominent backlink building categories that the top performing authoritative websites are getting links from.