I’m assuming when you say ‘each theme’ you mean, a different site?
Have you checked out the Installing Multiple Blogs page?
Yes, I meant a different website.
From the documentation (Installing Multiple Blogs)
…if you need multiple WordPress instances, you must actually install each WordPress separately (that is, as a separate WordPress installation). System architecture can be divided into two types by number of databases.
- Multiple databases installation. Each database manages specific site’s information.
- Single database installation. The database manages all site’s information.
Thank you for the information:)