Is the Siri watch face available on the Apple Watch Series 6 40 mm?

I just noticed your profile says you are running the watchOS 11 beta release. Apple has removed the Siri Watch face in watchOS 11. Sorry I didn’t catch that tidbit. The reason you don’t see the Siri face in the Face Gallery is because it no longer exists.

https://9to5mac.com/2024/06/14/watchos-11-removes-siri-face-on-apple-watch/

It’s available on my series 4 so it should be there for your series 6. Try powering down/restarting your watch.

Restart Apple Watch - Apple Support

Another suggestion I found by searching is to make sure Siri is turned on and active on your iPhone and Watch. If Siri is on you might try toggling it off/on and check the gallery again. Other than that take your watch to an Apple Store for inspection or call Apple Support as we’re just fellow users in these forums. Apple is not here.

Contact Apple for support and service - Apple Support

It must be available for your watch.