So, the Zen 3+ architecture was discussed yesterday during CES 2022, but I have not been able to find any documentation or whitepapers on it. Is there any reliable information out there yet about this architecture?
You can check AMD's Tech and Documentation site and see if there are any public docs concerning the Zen 3+ from here: AMD Technical and Documentation
If there aren't any then you can check at a later date and see if it has been added to the site.
This site might have some information in the future also: Data Sheets website
NOTE: if you are a developer that needs the information to create or manufacture a new product using AMD hardware then you probably will need to sign a NDA document to get AMD Non-Public tech documents.