Do you have to program for CU's?

I’m new to game dev and had an off the wall question. Let’s say you’re making a game and want to get the best performance out of the hardware, for example, the Xbox Series X. The Xbox has 52 CU’s I believe. How exactly do those work? Do you have to do a little work to get every CU working? What if you had released a game previously on one of the older consoles that has less CU’s. Do you then have to code to get every additional CU working on the new hardware, or do you make adjustments in the GDK to get all of them working? Or will they just all automatically start working and contribute to the load?