standalone php code outside wordpress?

Hello, I’m interested in finding out if there are any sample PHP codes available for retrieving related posts from a WordPress installation but outside of the WordPress environment. I need to display related posts on a subdomain of the same server where WordPress is not installed. The only available option for me is to utilize PHP and establish a connection to the database since both sites are on the same server and can be accessed through localhost. Is there a solution or code snippet that addresses this scenario?