I feel like when I watch people on camera, old-rich or born and raised and contiguously upper class people move their faces slower. Trump does not count, he is Nouveaux Riche i believe.
Their lives are theoretically less precarious so it kinda makes sense
I agree with the other commenters that you are probably seeing botox in the celebrities, or at least some kind of media training which makes them act unnaturally.
IRL, I’m not sure if it’s limited to posh people but I have noticed that smug people will often talk slowly - as if savouring the sound of their own voice - perhaps closing their eyes slightly as they are speaking as if in deep recall.