I think rhythm and overall dominance are way more important than "hitting certain spots".
By the end of the day you have the cock you have and she has the vagina she has, you can try different positions to try to stimulate different parts of her or in different ways, but trying to hit certain parts seems a bit weird.
Mostly I just try to go as deep as I can, tbh. My ex used to complain my D was big for her and hurt her, but last time we had sex she seemed to enjoy me going as deep as I could.
I guess I was lucky because my first gf and the girl I lost my V-card to came to me the first time we had sex. She came very easily to me with penetration, and we had lots of sex, so I got better and better, but I was already using the adapted missio position since the first time. A lot of girls like doggy I guess because of the animalistic nature of it and the domination aspect (like she's being taken from behind and stuff, not so personal, whatever), but this position is great for clit stimuli and overall vaginal stimulation as well, I think.
Just keep in mind some girls cum way easier than others, I guess it's a kinda genetic/evolutive thing.
Also bodies are very different from each other, so with some girls you might have an easier time stimulating their spots, while others not so much.