To get the 'Virtual Atmos' ideally you want to be playing something with the Dolby TrueHD and DTS-HD Master Audio codecThink the Atmos depends on how it is delivered. If it's via DD+ it seems to work fine via ARC.
Sure you you'll get 'Atmos "from Netflix /Prime selected content but in my experience to get the best out of the Bar 5.0, you want to be playing a 4K UHD disc.
Obviously this is just personal experience and I have my UHD player connected to my Soundbar
That's good if you can get "Atmos" without e you eARC as it does say to get the best experience you need that connection on your TV