Truthfully, it depends on so many factors and also luck. In my case, my greatest results can be traced to the sites I never thought would make much money. Since Google is now hiding most of the ranking metrics, most are trying to use what worked in the past as a guide. Before worrying about SEO ensure your content is up to par and your site layout is also good.
It is not the quantity of the backlinks but the quality that matters. Cheaper links promising to make you rank should be viewed with suspicion. I can assure you that in the backlinks business most often you get what you pay for, which means use common sense before purchasing.
Lastly, be wary of publicly sold PBNs. Better to build your own or find PBNs with a monthly subscription that is if you want to reduce the risk while also getting better performance metrics for your buck.