First of all Netflix does not support Dolby Atmos or DTS:X at this time. I believe VUDU and possibly HULU do but only over certain devices like xbox one, so even a $2,000 high end AVR will do you any good. I'm not sure why this is but you can research this and confirm it's veracity.
Second of all, ARC itself does not support these codecs. Until HDMI 2.1 hardware and it's eARC feature, you will not be able to pass Atmos from your TV to your receiver.
Although there are some limitations with ARC, as part of HDMI ver2.1 (which was announced in January 2017), eARC (Enhanced ARC) was introduced which ups ARC capability by accommodating the transfer of immersive audio formats, such as Dolby Atmos and DTS:X, as well as audio from Smart TV streaming apps.
In other words, on TVs that include eARC, you can connect all of your audio and video sources to a compatible TV and the audio from those sources can be transferred from the TV to the home theater receiver via a single cable connection. You should see eARC capability in TVs and home theater receivers beginning in 2018.
Unfortunately, TV makers don't always publicize what audio formats are necessarily supported on each specific TV, and not all details are outlined in the user manual.
However, since the introduction of the original Audio Return Channel feature in 2009, all TVs and Theater Receivers now incorporate ARC, but activation steps may vary for different brands/models - check your user guide for details.
Date published: 2018-09-04