How does the Max connections and max user connections work in mariaDB

I have a MariaDB server running 10 databases/users used for 10 different Wordpress sites.

I want to limit the resources so 1 site doesn't consumes it all. I think the max connections and max user connections is the variable I should play with.

So my main question is does max connections (default 151) limit the connections to each database or is it shared with all databases on the server?

And how do the max_user_connections variable work, is it connections per IP address that request data?

My goal is to limit the each Wordpress site from using to much resources and I want to limit the database connections to a minimum for each site.

Any help is much appreciated!