The guide doesn’t set an upper bound on the UHD quality profiles, but that doesn’t mean you have to set up yours exactly the same.
I have mine set with reasonable limits and have never run into a problem with file size, just have to make sure you’re setting the values to something that’s a) realistic and b) that you can live with.
One thing to note: if you set your threshold cutoffs properly you don’t have to worry about downloading files that are always at the upper end of the limit. Once the service downloads a file that meets the threshold it stops downloading for that episode/movie. If it grabs a file that’s below the threshold, it will keep trying to upgrade the file until the threshold is met.