It will be a good feature to have but Samsung will not do it cause its a Flagship exclusive feature. Its one of the features that seperates the Flagship and the midrange since most midrange now is almost on par with flagships.
You may set a Routine to do this. In my case, I always use 60Hz RR on most apps. But when a game is being opened, my phone automatically uses 90Hz RR. Bixby Routine is my solution in this case. 👌