Thanks for answering!
I would simply like to name the database differently than the default 'wordpress' since I can have multiple wordpress sites using the same MariaDB server. Would be really convenient to set it as a docker env var when running it, e.g. WORDPRESS_DB_NAME.
Maybe if I explain my setup workflow it is better understood or maybe I am overlooking some easier solution. I want to set up a wordpress site for a blog let's say. I create database 'wp_blog' and user 'wp_blog' with access rights to that db. I configure the Wordpress docker, however I can only specify database host, user and a password at this point. When I start the container and visit the site I would get message "Error establishing a database connection". The reason is that it expects database name to be 'wordpress'. So what I do in this case is
1) go to mapped volume /mnt/user/appdata/wp_blog/wp-config.php
2) modify the line
define( 'DB_NAME', 'wordpress'); to use 'wp_blog' instead.
after that everything works as expected and can continue installing WordPress.