As the title indicates, the problem is no audio is heard through speakers connected to the audio out jack on a clean install of Fedora 37 Gnome on a late 2014 iMac. A device listing indicates a Cirrus Logic CS4206 chip being used.
Unplugging the speakers resulted in playback through the built in speakers but nothing connected to the audio jack - speakers or headphones would provide sound. In settings the output device would switch successfully and the level meter there was displaying like there should be sound playing, but it wasn’t.
Went through a number of suggested fixes including installing pulse audio volume control, checking automute wasn’t enabled with alsa mixer. Eventually came across a post in a Linux Mint forum (Heaphone Jack (on iMac Late 2015 27'') does not work - Linux Mint Forums) which recommended creating a file called mac-fix.conf in /etc/modprobe.d with the following content options snd-hda-intel model=imac27_122.