There’s lots of sex referred to or implied in the books, but very little explicit. Yeah, that’s why everyone gives HBO/Benioff & Weiss shit for it, because they added it for entertainment’s sake. The LF brothel scene and Joff’s brutal birthday are both new. There is a place in ACOK where Tyrion considers sending Joff to a brothel, thinking it might sweeten him up a bit, but it didn’t come to pass.