I sometimes use my Raspberry Pi OSMC install on an HDMI TV and sometimes on an older set with composite video phonos. there are many posts about disbling teh HMDI output. Having just read the definitions (https://www.raspberrypi.org/documentation/configuration/config-txt/video.md) of hdmi_force_hotplug and hdmi_ignore_hotplug, it looks like I can force video output either to TRRS (on the 2.5mm jack) or HDMI.
It is understood that the device should, by default output to HDMI, but revert to composite otherwise. Mine seems to need forced into using composite even when HDMI is absent.
I wonder: is it possible to send output to TRRS, unless HDMI is detected, in which case, HDMI should be used?