Cloud Containers have MariaDB and MySQL tightly integrated, allowing you to manage databases, users and permissions directly through the Control Panel. In almost all situations when this documentation refers to either MariaDB or MySQL it will apply to both.
For other databases such as MongoDB or SQL Server, they are available to provision as Service Images, and are not integrated into the Control Panel. Instead you will need to manage these containers via CLI.
Cloud Containers have come with MariaDB installed out-of-the-box since late January 2024, prior to that they came with MySQL.