If you are interested in the new features, take a look here:
Interactive Architecture Diagram where you can get a very good introduction to oracle database with many pictures like this one:
This new feature i find very interesting:
Root Scripts Automation Support for Oracle Database Installation
Starting with Oracle Database 19c, the database installer, or setup wizard, provides options to set up permissions to run the root configuration scripts automatically, as required, during a database installation. You continue to have the option to run the root configuration scripts manually.
Setting up permissions for root configuration scripts to run without user intervention can simplify database installation and help avoid inadvertent permission errors.
But 19c is not released for on premise, so i have to wait for testing this feature: