As others said, it's how you use it, how hard it gets and other stuff.
My wife came hardest on a cock that was way smaller than mine.
Cuckolding is just in your head, it's your mental game on top. It's not really connected to your penis size.
i think a Cuckold with a big penis, being cuckolded by a "smaller" man is much more awesome because it turns the whole cuckold around.
I think there is a cuckold couple where the husband has a really big cock, but is in chastity for a long time. AlisterMonsterCock or so.
Everyone with a small cock can do SPH and Cuckolding, but it takes much more and is more interesting if hubby is bigger but still in chastity 🙂