In your docker compose, you defined where on your host system the container writes for /config, right? On the host OS go to that folder, in /config is another config folder. Create logging.json there.
Jellyfin 10.10.3 (Docker)
Ubuntu 24.04 LTS
Intel i3 12100
Intel Arc A380
OS drive - SK Hynix P41 1TB
Storage
3x WD Red Pro 6TB CMR in RAIDZ1 (JF Library)