Install mariadb, and run the following command before starting the 
mariadb.service

mariadb-install-db --user=mysql --basedir=/usr --datadir=/var/lib/mysql


To administer the server, run mariadb as the user running the server: 

[mysql]$ mariadb 

or as root 

# mariadb

Add user

Creating a new user takes two steps: create the user; grant privileges. 
In the below example, the user monty with some_pass as password is 
being created, then granted full permissions to the database snukdb:

# mariadb -u root -p

MariaDB> CREATE USER 'snuk'@'localhost' IDENTIFIED BY 'some_pass';
MariaDB> GRANT ALL PRIVILEGES ON snukdb.* TO 'snuk'@'localhost';
MariaDB> quit

more details:

https://wiki.archlinux.org/title/MariaDB