Yes, to get Atmos audio you will likely find the TV requires an HDMI eARC port - as some uncompressed atmos codecs like DD TrueHD (atmos) require greater throughput which HDMI-ARC is not capable of, although some compressed formats like DD+ (atmos) may work okay.
Anyhow all is not lost, as it is possible to bypass the TV for audio purposes with an audio splitter/extractor. There are two on the market that I’m aware of at the moment, one is the HDFury Arcana and the other is the Feintech VAX04101A. See links below to read more about those two devices.
Arcana:
https://www.hdfury.uk/product/hdfury-arcana/
VAX04101A:
https://feintech.eu/en/products/feintech-vax04101-hdmi-earc-pass-switch-4x1
Many thanks Ken, I'll take a look to it!
With a similar situation, the HDFury Arcana worked for me.
But the other problem I had was that the Fire Stick proved to be useless at passing Atmos. I don't know if that is still the case but I bought an nVidea Shield Pro and that has been great.
So it's nVidea Shield to Arcana
Arcana HDMI to 2016 LG OLED TV
Arcana eARC to Sonos Arc
Using the HDFury Arcana, the Fire TV Stick 4K Max should support Dolby Atmos on Netflix, Prime Video, and Disney+ but not on VUDU, HBO Max, or Apple TV+. If you want Atmos support on all of these apps, get an Nvidia Shield like @John B or an Apple TV 4K. With the Apple TV 4K you can also enjoy Dolby Atmos/Spatial Audio music on the Apple Music app.