The way that CEC is written, it looks for a single ‘sync/speaker’ connection, and uses that. In order to use the Bluetooth connection in your TV set, you’d likely need to just turn off CEC in the TVs settings. 

An option (which you may not like, or agree with, but you did ask ) is to return the ear buds but keep the Arc.  Or try Bruce’s suggestion. 

That is a great answer. My compliments! However I will try Bruce’s response. I do thank him for that.

What if I just disconnect the  LG HDMI ARC  input & blue tooth the buds to the LG, and reconnect that HDMI ARC  when I am through using the ear buds?

That’s an interesting question. I’m not sure exactly how the computer in the TV works when there’s not something connected to the HDMI port...but I’d assume that since the CEC (or whatever they call it) is either on or off, without respect to an actual cable.. Fairly easy to test that theory on your own TV :)

I think the easiest thing to do is just turn off the CEC in the TV’s controls, without having to do any disconnect of the HDMI cable, and then pair the ear buds.  Again, testing would be key here, as this is not something I’ve ever done. My TVs (Visio) has no bluetooth connection. 

Thank you Bruce, once again. I am considering another possibility, using an optical audio adaptor and feeding the send to a Bluetooth transmitter. That also might work. I will try these alternatives this weekend, when they will have finished painting my home. Getting behind my TV is no easy task. My 91 year old knees (a gift of the US Army), tend to make me swear like the former CSM I once was. My wife leaves the room, it may have to be the house this week end.

Thanks again, Hank

I have found this out thus far. Switching out the speaker via the CEC, as Bruce suggested did not do it. 
disconnecting the ac line to my SONOS, did allow the Apple buds to work with the LG Bluetooth circuit quite nicely.
I will now try to use an Alexa controlled AC outlet to turn the SONOS  ARC, on and off by voice command. If it works,
I will have resolved using ear buds in a easy and inexpensive approach.  Will let you know.

I have found a successful way to use my apple ear buds pro with my Sonos ARC & LG OLED TV.

I hooked up the ARC power cable to an Alexa controlled outlet, I tell her to turn off the power to my ARC, and seconds later LG Speakers take over, allowing my Apple ear buds via LG Bluetooth access to the TV audio, With their volume con trolled by the LG Volume control. When I no longer require the ear buds, I simply say “ Alexa turn on the Sonos Power.”. It returns power to the ARC, which restores its control of the audio, which auto disconnects the Bluetooth connection. Hank