Currently limited at full HD resolution due to battery life-related concerns, the 120 Hz display refresh might soon become available for the Galaxy S20 lineup since Samsung is reportedly working on a software update that will bring WQHD+ 120 Hz capabilities. Its launch should take place by the end of April.
https://www.notebookcheck.net/WQHD-120-Hz-software-update-allegedly-coming-soon-to-the-Galaxy-S20-series.454245.0.html
The only reason that keeps me from buying the s20 is exactly the lack of 120hz at wqhd