“Prominence is also based on information that Google has about a business, from across the web, like links, articles, and directories. Google review count and review score factor into local search ranking. More reviews and positive ratings can improve your business’ local ranking. Your position in web results is also a factor, so search engine optimization (SEO) best practices apply.”
“Tip: There’s no way to request or pay for a better local ranking on Google. We do our best to keep the search algorithm details confidential, to make the ranking system as fair as possible for everyone” Google.