Installing MariaDB server from the Fedora Modular repository
To list the available versions (_streams_ in modularity terminology) of MariaDB:
$ dnf module list mariadb
To enable the version of MariaDB you want to use and make the stream RPMs available in the package set:
$ sudo dnf module enable mariadb:10.4
At this point you can verify that the available RPM provides the 10.4 verison of MariaDB server:
$ dnf list mariadb-server
To install mariadb server:
$ sudo dnf module install mariadb/server
or simply, as usual:
$ sudo dnf install mariadb-server
With modules, you could also install a specific profile: like client, devel or galera (the multi-master replica).
For instance, if you don't want to install the server stuff, but only the client packages:
$ sudo dnf module install mariadb:10.4/client