A racecar is never just a set it and forget it type of machine.
Each circuit determines the sort of setup a driver and a car might prefer, as it might have a tight, corner heavy layout or one that's more open and filled with high-speed sweeping sections. Now, you make this about rally racing and you can add in tarmac, gravel, dirt, snow and all sorts of other surface types and it just adds to the many ways in which you can setup your racecar.
Wyatt Knox from Team O'Neil Rally School is here with an explainer on how they set up their own racecars. He's created a list that you'd work through before hitting the track. You want to start at the top, which is where the most complex items sit, and work your way down.
Knox notes that once you're at the track and need to adjust things, you then work your way through the list in the opposite manner. This is because it's easier to tweak the more simple elements before diving into more complex items.
At the top, you'll find spring rates and the ride height. This affects how your car sits and also how it responds to all the bumps, dips, and imperfections in the stage. At the bottom of the list you have more simple elements like tire pressure and brake bias. These can be quickly changed, and it might be enough to better prepare the car for what lies ahead.
This is a long video, but watch it in segments and take notes. Wyatt knows his stuff and he's giving you a lot of information for free. So if you're truly curious about building a racecar, then you need to pay attention.