Maybe it would help you to understand that the eARC port is just another HDMI input. It functions like any other input but also is the only HDMI connector that has audio out.
HDMI In To HDMI and eARC Out - How Do I Do This?
I am running an Apple 4kTV into a LG OLED TV and have a Devialet Dione sound bar. The TV does not output eARC to the soundbar. How do I split the output from the Apple 4kTV to get both an eARC signal for the soundbar and HDMI signal for the TV? I looked on Amazon and I am unsure which splitter to buy. Your advice/guidance would be much appreciated.