Search for "PC2 Race Randomizer" on GitHub (created by user "TheIronWolf" or similar community forks). Look for the latest release (v1.2 or higher). Download the .exe or the Python source code. Do not download from suspicious adfly links.
The most direct way to get a randomized setup without downloading additional software is the Project CARS 2 Randomizer How to use:
But after you’ve mastered the GT3 class at Spa for the thousandth time, a certain fatigue sets in. You know the track. You know the car. You know the optimal setup. The magic of discovery fades.