All the existing UHD 4K gaming monitors support 4K@120Hz on PS5 and Xbox Series X, please stick to following steps to enable the function.First of all, make sure the game title supports 120Hz refresh rate.
  PlayStation®5
 1. Update PS5 firmware to the latest version (release date after 2021/4/14)
 2. Turn to Settings and select Screen and Video
 3. Turn on Enable 120Hz Output in Video Output section
 4. Done.  
 
  Xbox Series X
 1. Enter General and select TV & display options
 2. Change Resolution to 4K UHD and Refresh Rate to 120Hz in the display section
 3. Done.  
 
  Support list of 4K UHD@120Hz Gaming Monitor (until 2021/4/16): AORUS FI32U, AORUS FV43U, AORUS FO48U, GIGABYTE M28U, GIGABYTE M32U