Aside from the move to the Snapdragon 855 Plus and faster UHS 3.0 storage, the Red Magic 3S doesn't introduce much else to the table. The display, for example, remains relatively dim compared to the competition at under 300 nits maximum even though colors are slightly more accurate this time around.
https://www.notebookcheck.net/Nubia-Red-Magic-3S-display-appears-to-be-better-calibrated-than-the-original-Red-Magic-3.446000.0.html