Like several others in this thread, I would be extremely suspicious of attractive women approaching me randomly with offers for sex - my first thoughts would be to assume either she was a prostitute, it was a practical joke by some girls having a night out, it’s a scam/setup or it was one of those hidden camera shows etc.
To address the OP, when I was younger there was the girlfriend of a colleague who made it very clear, in increasingly certain terms, that she wanted to hook up with me in a way neither of our partners would approve of.
My polite rejections (“I’m flattered but spoken for”, “I’m seeing someone, but thanks anwyay”, “We’re both in relationships so this isn’t something I’m comfortable with” etc) didn’t work and only seemed to encourage her to try even harder. Other people noticed this (and also noticed my continuing polite and civil rejections), so it wasn’t something that was being taken out of context.
It finally culminated one day when she said she had a hotel room on the other side of town for some implausible reason and I should “come and check it out [with her] because it’s got a great view from the bedroom”. I flatly told her no, it wasn’t going to happen, I wasn’t interested, stop it, etc.
Her reaction was the (as mentioned by other posters) classic “OMG, you thought I meant it like that! Pfft! Don’t flatter yourself, weirdo,” etc. There was some drama when she told her boyfriend I’d been hitting on her, but that was very quickly sorted out when half a dozen people came to my defence and said it was the other way around and she’d been hitting on me and I hadn’t wanted a bar of it.
Anyway, I later had a female colleague (at a different job) develop a romantic interest in me, and remembering the dramas from last time, I just played dumb. You want to go to a movie? Sure, which one? That one? Sorry, my girlfriend doesn’t like [the actor/genre] and doesn’t want to see it/My girlfriend is working then and can’t make it. Let’s get coffee? Sounds good, my girlfriend wants to come along as well.
I wouldn’t comment if she was wearing more makeup or jewellery and would talk about the cool stuff my girlfriend and I had been up (we went to a winery at the weekend, it was great!) and so on. After about two months, my colleague worked out I wasn’t interested and there was no drama, unpleasantness, or hurt feelings.
Having said all that, I think most guys would agree it’s quite unusual for women to blatantly hit on them unless they look like Ryan Gosling or Gerard Butler. It’s just not how things generally work, in our experience.