You'll need a transmitter as no Smart TV I know does this.
There are so many transmitters that I can't pick it for you so your choice as well as finding what outputs the TV has. Some don't have audio out and many will NEVER send more than stereo. If you attempt to send HD Audio, I expect this to fail.
Frankly I would NEVER DO THIS. The chances of discovering lip sync issues is about 98%. Get a sound bar or audio system.
I enjoy listening to Spotify over my Chromecast audio powered speakers using a Google Home app as an interface on my IOs phone over WIFI. I'd also like to be able to also cast audio wirelessly coming from my Smart TV (TLC Roku) to my Chromecast audio powered speakers. Do I need a transmitter? What TV device will Google Home recognize in order to pair with my powered speakers? Thanks so much!

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