Size doesn’t matter...

I always hear woman say “it’s not the size that matters, it’s what they do with it” in reference to sex. My boyfriend is maybe 5 inches? The sex is great with him but I never understood when people say the size has nothing to do with how good sex can feel. What moves do guys do to make sex better? Is it the position? My bf and I are both pretty new to the whole sex thing, but I’d just like some insight on how to possibly make it even better.