32GB is overkill for most Plex servers

Yes, for a typical home server running Plex and a handful of Docker containers, 32GB is more than you need.

Plex itself barely touches RAM unless you’re doing heavy live transcoding. Docker containers vary, but 16GB is comfortable for a dozen services like Sonarr, Radarr, Home Assistant, and a database or two. 32GB starts making sense only if you’re running multiple VMs, a media database that sees heavy queries, or you’re hosting for a dozen concurrent 4K transcodes.

If you have the money and want to future-proof, it won’t hurt. But you won’t see a performance difference over 16GB for the typical Plex-and-Docker setup. Spend the extra cash on storage or a better CPU.