Arduino_GFX available in Library Manager as GFX Library for Arduino .
And it doesn't work for you?
Please provide a link to your display. Is it an Arduino UNO shield? What controller does it have? Check controller ID with MCUFRIEND_kbv on Arduino UNO R3.
If it doesn't work, report the constructors you used.
See also https://forum.arduino.cc/t/uno-r4-wifi-3-5-tft-lcd-shield-white-screen/1195026/17,
if needed, copy the new driver class from my fork.
-jz-