Does the Sony TV own built-in Apps support Dolby Digital Plus…? If not then it’s unlikely the TV will pass-through that audio, you may have to consider by-passing the TV with a HDFury Arcana audio extractor to achieve the outcome you are looking for.

Note you will definitely not get Dolby TrueHD, LPCM Atmos using an Arc port connection the TV will need HDMI-eARC to the Receiver for those type of uncompressed formats. I suspect your Sony TV is perhaps limiting things here.

Thanks for answering. 

Yes, tv apps supports Dolby digital plus. I tested Amazon prime and Netflix native apps. 

You may want to try Jack Ryan on Prime as that has Atmos and ensure you have the correct ultra-HD subscription for Netflix, otherwise you may only get Dolby Digital 5.1 audio anyway.

I don't think the tv apps allow Atmos but definitely 5.1. The problem is the Google tv connected to the tv. Apps at Google tv only getting stereo. 

Are you certain the TV supports DD+ and not just DD 5.1? If it’s the latter and you have set your connected devices, like Google TV to use the DD+ as its audio-out codec, then you may only get stereo in those circumstances - or the TV may not support the pass-though of either codec.
 

Perhaps check the TV/Google TV user manual, or speak with Sony Support and see what they say. The fact the TV built-in apps are working with DD5.1, eliminates the Sonos Arc as being your issue.  

Here is a useful guide showing what apps/devices support Dolby Atmos:

https://www.nakamichi-usa.com/the-ultimate-dolby-atmos-guide
 

More than likely, your TV doesn’t support Atmos pass through, so you will have to either get a new TV with eARC or get the HDFury Arcana to be able to get Dolby Atmos audio from your Roku Ultra, Chromecast with Google TV, or Apple TV 4K.

This is a seven year old TV: chances of Atmos support are zero, chances of messing with a DD 5.1 signal from an HDMI source are ~25%. Try the optical port from the TV to the Arc instead, TVs mess with the optical path less often.