Question about LG 43QNED86A6C

Depends on your budget and your requirements. Useful headphones are available from 30 - 500 CHF. In any case, they should work wirelessly with Bluetooth. Noise cancelling is an advantage. If you want to use the headphones as a hands-free unit with your mobile phone, they should also have a built-in microphone and allow simultaneous Bluetooth pairing of several devices (e.g. phone and TV). If you're not sure what's best for you, I've found it useful to google, for example:
"Test Bluetooth headphones"
This will give you an up-to-date overview of the devices for orientation.

I didn't plug in headphones, but an external loudspeaker, and it works very well.

I'm very happy with the SOUNDCORE AEROFIT 2 headphones; the price-performance ratio is right for me.