There’s an existing feature suggestion asking for that. I suggest you vote/comment in that thread to avoid distracting/dispersing votes.
https://forums.plex.tv/t/hover-animated-thumbnail-preview/541331
There’s also a suggestion asking more generically about support for animated posters (not based on preview frames)
Therefore closing this thread.
(please don’t take this as discouragement – suggestions are more than welcome… there’s just so many duplicates)
