Nothing you can do about this. AutoPlay video is blocked by browsers, until you have a “good interaction score” with your website, which is confused by google sites and wix usage, due to multiple iFrames…
So that is a can’t fix due to browers technology literally preventing it
Owing to browser permissions each iFrame in the stack requires the fullscreen permission which might not be granted and that is a thing you can’t change on Google Sites or Wix.
You’ve allowed it in the video/embed set, but each iFrame in stack might not allow/grant the permission.