Life experience, sure, 20 years' worth. Wisdom, presumably--that often comes with the life experience. Better in bed? Well, obviously she's been with someone other than MC (because he just can't be the twins' father), but how long has it been? I don't think Alyssa's said word one about her father, and it doesn't seem like Scarlett would be dating a whole lot with young kids. By the time we meet her in 2019, she's alone and nostalgic for MC. Hot as 1999 Scarlett is, I don't think 2019 Scarlett has gotten much action for a long time, which would work against the "better in bed" assumption.
Not trying to disagree with you and just trying to make my point of view clearer but when I said being better in bed with age it was in the perspective that just because we got a lot of experience in the sack and more partners that will mean a better experience, most times it does though.
May happen (or not, not everyone grow better with age) that she sees sex in other perspective, that isn't just for their own pleasure, and more sex or less they know better their own bodies and mind.
Sex isn't just physical, it is also a state of mind and the most probable difference is how you treat your partner and how you share the experience. And that was why I mentioned that older women (and men) probably get better in that aspect, if I have to chose in terms of sex between a 18-25 yo or a 30+ yo same version of a women I'll always chose the latter, independently of their sex experience and number of past partners.
But with a 18-25 yo as a partner there is the plus that you will experience that growth together of course and that is an incredible experience as well.
Of course the upside probably the younger version may be more energetic, flexible, smoother with all "still in place" lol but also still exploring their own sexuality and more often than not still doubting themselves and in my experience things don't flow so naturally.
The downside is that older women (and men) carries more "baggage" hehe and that can be an issue as well if that baggage is negative.
Just a matter of preference really. Maybe that is why "deflowering a virgin" kink, specially a younger women, never been one of my kinks and never will be.