Tipster @UniverseIce stated that current firmware for the Samsung Galaxy Note 20 Ultra supports QHD+ resolution and a 120 Hz refresh rate, but not both at the same time. Since this is a feature other devices like the OnePlus 8 Pro already support, we expect that a post-launch update might add this option in.
https://www.notebookcheck.net/Tipster-says-Samsung-Galaxy-Note-20-Ultra-will-get-120-Hz-refresh-rate-and-QHD-resolution-but-both-won-t-work-at-the-same-time-unlike-the-OnePlus-8-Pro.481419.0.html