Apple TV 4K and Dolby Vision & Atmos

Apple TV 4K →[HMDI]→ AV receiver ⇄[HDMI (e)ARC]⇄ TV

If your AV receiver has had all of its firmware updates, then I think it should be able to do Dolby Vision passthrough. Yahama lists DV compatibility on their website for this model.

The receiver should have configuration for 4K Mode as Mode 1 or Mode 2. Set Mode 1 for high bandwidth use (up to 18 Gbps [HDMI 2.0]). Mode 2 would be for use up to 10 Gbps [HDMI 1.4].

Set your Apple TV video settings as they should for this setup, else you may not get what you intended. Set YCbCr color space (not RGB). Do not set 4:4:4 chroma, instead use 4:2:0. This does not diminish the video qualify in any way, as all streaming video is encoded as 4:2:0. [4:4:4 would use double the HDMI bandwidth, which would block certain other video features to stay under the bandwidth limit of the used HDMI ports, when any of you devices has HDMI 2.0 ports (instead of HDMI 2.1) — e.g. like your 2016 receiver.]

Then Dolby Vision should be selectable on Apple TV as video output format.

4K mode

From the online Owner’s Manual (PDF): p.153, p.155.

Advanced Setup Menu (front panel and LED display):