The HDMI 2.1 and eARC specs are really about bandwidth to improve video content. Audio is typically just along for the ride as it doesn't take up much room. The main difference between HDMI ARC vs eARC comes down to bandwidth.
Support for all relevant audio codecs isn’t compulsory, so one can’t simply assume that a TV will be able to send a 5.1 Dolby Digital or a DTS soundtrack from a movie over ARC. Some TV manufacturers only support Dolby Digital, while others only support two-channel stereo. So check your manual, but yours is new enough to hopefully send what you are looking for.
It’s worth noting ARC doesn’t allow you to bitstream the high-quality codecs such as Dolby TrueHD, Dolby Atmos, DTS-HD Master Audio or DTS:X soundtracks that you find on Blu-rays and 4K Blu-rays. If you want this level of functionality, you’ll need HDMI eARC. But the Apps that I use don't transmit in any of these Lossless Codecs, and I've heard some ISPs (Internet Service Providers) won't allow it due to the increased bandwidth, but that too should be fading as networks gain capacity.
ARC can, however, allow you to receive Dolby Atmos audio from streaming services such as Netflix, Disney Plus and Amazon Prime Video, as these services embed Dolby Atmos in the lossy Dolby Digital Plus format which ARC can handle.
As I mentioned above, I haven't been impressed with the sound quality from Apps yet. Last August we treated ourselves to a new 75" Samsung QLED set, and while we are very happy with it, the sound we get from Amazon Prime, Netflix, and Disney+ via eARC is plain old sad when compared to Blu-ray disks. I certainly wouldn't jump into a new Receiver for sound from those sources.
I too let the TV do any up-conversion of video as it does a better job than my receiver. (I checked & was surprised). Some day real HD Sound will come from the Apps. I'm waiting for it too.
