In march 2018 i wrote about the new installation procedure of oracle database 18c via rpm, which was announced inside the "new features".
The installation guide for Linux contains now the commands for installing the database via rpm. Here a screencopy of chapter 11:
rpm -ivh oracle-ee-db-18.104.22.168.0-1.x86_64.rpm
The next step is to run the dbca:
7 The screen displays information that prompts you to create a database by using Oracle Database Configuration Assistant (Oracle DBCA) in silent mode.
Oracle DBCA creates the Oracle Database listener, the Oracle Database instance, starts the instance, and completes the Oracle Database creation process. Review the status information that is displayed on your screen.
Here the link to docs.oracle.com chapter 11 "Running RPM Packages to Install Oracle Database".