Microsoft announced the general availability of SQL Server 2019 on November 4th 2019 at its Ignite conference. There are four editions: Enterprise, Standard, Express, and Developer. Express and Developer editions are free and can be downloaded from microsoft.com/en-us/sql-server/sql-server-downloads.
A list of new features for SQL Server 2019 is also available.
More information is available at microsoft.com/sql-server/sql-server-2019 and the Tech Community site.