Do I need both primer and setting spray?

Excuse me, I'm a bit confused about the makeup routine for a flawless complexion. I've heard about primer and setting spray, but I'm not sure if I need to use both of them. Could you please explain the purpose of each product and whether they are both necessary for achieving a long-lasting, smooth finish? Also, do they work well together, or should I choose one over the other depending on my skin type or the occasion?