Vitess is not a database system itself, instead it is an overlay on top of MySQL.
Vitess provides a sharding system for MySQL, as well as some operational management for its instances. Vitess will assist with actions like sharding, managing backup and restore, and splitting, combining, and adding replicas.
However, it is important to note that implementers of Vitess will need to provide their own MySQL and perform their own MySQL management. The amount of MySQL management required depends on if Vitess is configured to run with "integrated" MySQL (i.e. MySQL managed by Vitess) or "external" MySQL.
Vitess can run against various flavors/implementations of MySQL, e.g. MySQL Community Edition, MySQL Enterprise Edition, Percona Server, MariaDB Server. Vitess can also be used with many Cloud deployments of MySQL, e.g. AWS RDS, AWS Aurora, GCP Cloud SQL, etc.