The Google app looks to be getting user voted tags for movie searches in a future update as some users are now reporting that when searching for movies within the application they are seeing a new section that shows up which is called Top voted tags. These tags will be similar to what you'll find on YouTube videos and will have categorizations to help describe the movie. When searching for movies with this new feature enabled there will be some tags already present, but there will also be a button that spans the width of the display which says "vote for tags" and when pressed it will bring up a window which asks users to describe the video by tapping any number of the listed tags, which could include things like memorable characters, amazing music, must watch, and more, and below all the options there will be a text entry field for users to suggest a new tag.
When Google plans to roll this out to all users is uncertain and it's not clear exactly how wide spread this is, nor is it clear exactly which regions Google is testing this so it could be limited to specific regions around the globe. For now the takeaway is that it's not available to everyone.
Having said that, it's entirely possible that Google may decide not to keep this feature and it may never go beyond a test period with the users that do already have access to it. Whether or not Google makes it available to all users will probably depend on how well-received it is with those that are testing it right now, which should make sense as Google tends to grab feedback from users on many of the features that they do end up implementing. There isn't any explanation on whether or not you'll need to have a specific version of the Google app installed to see this, so it's more than likely just a server side change that Google pushed out to select users and it may have no relation on the app version that users have installed on their devices.