We only allow one database per WordPress site.
With Database Hosting, you can host as many databases as you want.
Note: For WordPress sites, we recommend that you use our Managed WordPress Hosting as opposed to Application Hosting and Database Hosting. Managed WordPress Hosting is built, designed, and optimized by Kinsta to serve WordPress sites. It includes everything you need out of the box, such as full-page caching, backups, and the ability to update plugins and themes easily.