CoreCtrl

CoreCtrl lets you set your AMD GPU and/or CPU to high performance when you play games.

Please note: this application does not work for Nvidia hardware.

Installation

Search CoreCtrl in your respective app store:

If you don't see it there, and you're on a Ubuntu-based distribution like Pop!_OS, input the following in the terminal:

sudo add-apt-repository ppa:ernstp/mesarc
sudo apt-get update
sudo apt install corectrl

Otherwise, look here for installation instructions.

Set your GPU to Performance mode: Fixed > High.

Set your CPU to Performance scaling > Custom.

Then, set your frequency governor > Performance.

You can do more with it, for example overclocking, or undervolting. You have to do the setup first.