Some XDA contributors have posted on new mods that increase the display refresh rate of the Redmi K20 (or Xiaomi Mi 9T) and K20 Pro to 75 hertz (Hz). This mirrors earlier unofficial development work on the Mi 9. By all accounts, these mods work well, but may be detrimental to battery life.
https://www.notebookcheck.net/New-mod-brings-74Hz-refresh-rate-to-Redmi-K20-series-screens.428192.0.html