We put selected versions of the software to download for trial purposes etc on www.oracle.com. Typically they are the most current version of the software *at the time of release*, and are subject to the terms of the license that you click "Accept" when you download:

https://www.oracle.com/downloads/licenses/standard-license.html#licenseContent

For example, you can the 19.3 version for Linux here

https://www.oracle.com/database/technologies/oracle19c-linux-downloads.html

But we also release updates to that software. That's where support.oracle.com comes into play, because it it going to contain the most updated distributions, plus release updates etc. (It's also why support.oracle.com is part of your oracle license).

In any event, I would not be downloading a 12.2 because its about to go out of support - go with 19. But you can always get old software releases from

https://edelivery.oracle.com/