In Pathfinder non esistono regole ufficiali per livelli "epici" ovvero oltre il 20. Lasciano aperta la possibilità di usare HR o materiale third party compatibile per proseguire, ma la Paizo non ha mai rilasciato nulla di completo direttamente. Trovi solo sul manuale base delle linee guida per far progredire le classi che loro stessi ti avvisano essere incomplete e a rischio.
Although classes doesn't describe what happens after 20th level, this isn't to say that there are no resources available to you should you wish to continue your campaign on to 21st level and beyond. Rules for epic-level play like this exist in numerous products that are compatible with the Pathfinder Roleplaying Game, although in many cases these alternative rules can provide unanticipated problems. For example, if your campaign world is populated by creatures and villains who, at the upper limit of power, can challenge a 20th-level character, where will epic-level PCs go for challenges? You might be looking at creating an entirely new campaign setting, one set on different planes, planets, or dimensions from the one where your players spent their first 20 levels, and that's a lot of work.
The following are brief guidelines to continue play beyond 20th level. These guidelines aren't robust enough to keep the game vibrant and interesting on their own for much longer past 20th level, but they should do in a pinch for a campaign that needs, say, 22 or 23 experience levels to wrap up. Likewise, you can use these rules to create super-powerful NPCs for 20th-level characters to face.
Poi ci sono le regole mitiche, ma quelli non sono appunto livelli e anche se un pg X 20/mitico 10 corrisponde a grandi linee a uno di 30° non ha effettivamente le statistiche di uno di 30°.