How do I overclock Raspberry Pi 4 with Ubuntu to 1.75Gh and 600 on GPU

[Pokemonbulbasaur]

I want to overclock ubuntu 20.04 to 1.75Ghz and underclock back to 1.5GHz if temperature reaches 90 degrees Fahrenheit

[jamesh]

I presume you mean centigrade since 90F is only 32C, and the Pi would normally throttle at 85C

You cannot increase the throttle temperature to 90C, it's hardwired in to the firmware at 85.

[DMMG]

did you do it ? how?