This guide makes your Vivo X90 Pro Plus to run consistently at 144hz. This can be used to save some battery (if you use 90hz) vs 120hz and keep the smoooooooth animations against 60hz.
1 – Connect the phone to the PC with adb;
2 – Open a prompt command and insert the following commands:
settings put system peak_refresh_rate 144.0 settings put system min_refresh_rate 144.0 settings put global vivo_screen_refresh_rate_mode 144
(If you want 90hz just replace 144 for 90)