This has been posted before, but it appears the previous thread was closed (https://www.googlenestcommunity.com/t5/Chromecast/Chromecast-with-Google-tv-won-t-Autoplay-Netflix-o...)
At least when playing through the Netflix app on iOS via my phone, Netflix does not autoplay. I have confirmed Netflix is set to autoplay on my account, and confirmed that this issue happens with multiple Netflix accounts that are both able to autoplay without issue on a Chromecast Ultra elsewhere in my home.
It seems to me that the branch of the Netflix app for the Chromecast with Google TV does not correctly implement autoplay.
Hey there itemduper,
Thank you for visiting the Chromecast Community! Since this thread hasn't had activity in a while, we're going to close it to keep content fresh. We hope you were able to get the help you need, but if you're still having issues, please reach out to Netflix Support.
If the issue persists, feel free to create a new thread, and provide as many details as possible so that others can lend a hand. Hope this helps!