I've experienced 3m living rooms quite often, but I think it doesn't feel cozy anymore.
We have 3 m high ceilings in the old building. I think it's great and you have the chance for a chandelier or a loft bed. In the new building, the cost-benefit analysis only allowed for 2.55 m. Well, that's how it is, there are worse fates and somewhere you also save steps to the upper floor (which again gives back so much lifetime :rolleyes ...
Ugh, chandelier. We have our ridge in the upper floor open up to 3.80m for the loft bed; with the exposed beams, it still feels spacious despite the knee wall of 90cm. But for a living room, it wouldn’t be my thing.