This is an update on this issue.
I tried two more approaches to this issue, which consistently freezes when The Dark Templar Helmet from The Debaucheries of Derketo Pack DLC appears on the screen.
1: PS Conan Exiles (North American version)
⇒ The game ran normally and did not freeze when The Dark Templar Helmet appeared on the screen.
2: PS Conan Outcasts (Japanese version)
⇒ The game froze 100% of the time when The Dark Templar Helmet appeared on the screen.
Therefore, this issue is likely a problem that only occurs in PS Conan Outcasts (Japanese version), and is a bug that arose during the localization process.
Japanese PS players are always at risk of never being able to log in to the same server again. I hope this issue will be fixed soon.
Additional Note
The freezing issue does not appear to occur on the PC version (Steam).
Also, the Dark Templar Helmet is written as “闇聖堂騎士のヘルム” in Japanese.