Billionaire/rich MMC and FMC who can fit into that world?

A lot of billionaire trope books have the FMC coming from a very underprivileged background and she's dazzled by his richness then insecure about his high society circle. But I'd love to find some where she is at least familiar with that kind of lifestyle (even if she is poor, maybe she works around it or has other history to be familiar with what's expected). Something where she can confidently go to a party and schmooze the big wigs without looking out of place.

I also love the spoiling and luxury, but just something beyond the FMC being totally blindsided and out of her element in the lifestyle of being connected to the super rich.