Using Fiverr to boost Google Ranking through link-building

Hello community,

Over the last month, I have been working on improving my Google Ranking and Domain Authority through dofollow link-building. My strategy have been buying links off people on Fiverr.com. What I do is buy an article on one of their PBN sites, with a link to my site. Now here comes my question. I have just noted that most of these PBN websites, where I buy an article, have been using alot, if not only Google domains to link to their site. Does this mean that their DA have been increased artifically with this method? That they don't really have a high DA, they are just exploiting the Moz system, and are still bad ranked on Google? Does this also mean, that having their website link to mine doesn't have any effect? Or maybe it does? If their site is just a bunch of artifically improvements through Google. Hopefully someone in here have some insights or experience! :) thanks in advance, and looking forward to hearing from you and having a talk. Best regards