So I think I have this figured out so bear with me here.
I'm using vedic as well as western techniques here so bear with me.
One thing to remember sex appeal and beauty usually coincides but not always but I don't know how strong sex appeal without beauty is but I do know what beauty with sex appeal looks like and I've researched this.
For one to be generally beautiful, venus needs to be on the asc, OR as the highest degree planet, OR conjunct the highest degree planet in the chart, or needs to be the asc lord. Venus aspecting the asc is also pretty good.
Neptune can also be very beautiful but I've seen this changes the appearance though surgery, enhancements etc like Marilyn monroe or kim or kylie kardashian.
Now a very beautiful woman will have venus(if her asc lord or highest degree planet) exalted, or in a friend's sign, OR another planet that is either the asc lord or the highest degree planet exalted or in a good sign.
An extremely beautiful woman will have libra and scorpio involved somehow when it comes to their asc lord or their highest degree planet or asc.
Now if you want an extremely beautiful woman with sex appeal, moon in scorpio woman always stand out. I'll name them if you want me to: they've all been it girls: Scarlett Johansson, Elizabeth Taylor, Margot Robbie, Beyonce, Jennifer Lopez, Mila Kunis, Adriana Lima.
What do all these women have in common? Yes they are pretty but so are lots of hollywood women, but they were all considered IT girls at some point in their own ways.
Now Adriana Lima has all these things in her chart.
She is a pisces asc, with venus trine her asc, and jupiter(the ruler of her asc) is in libra. For sex appeal, she's good moon in scorpio as well.
Other 8th house, scorpio, libra, taurus, pluto, and even mars will make for some sex appeal and will probably contribute to the persona of the person. But I've never ever seen any aspect that outshines everyone in sex appeal like moon in scorpio. I personally think neptune people are extremely attractive and I also heard mars conjunct neptune also really causes magnetism. (bradley cooper and ryan gosling has this) Probably because it's a water planet with a firey planet which mimics how scorpio is born. Which brings me to my final point which is I do think the way you carry yourself and your persona you exhibit can make you more enchanting.
Mercury as asc lord or highest degree planet can make someone attractive but I feel like venus is beauty and sex appeal put together and it usually gives a very provocative look. But unlike venus, mercury as highest degree planet, or on the asc or asc lord never really have to get worried about gaining weight or looking old.
Unlike venus, it stays thin and young. And unlike neptune, it's actually beautiful and doesn't enhance itself through tricks.
I'll link you up with two videos I think you'll find interesting.
https://www.youtube.com/watch?v=DafaKnWu0Qk
This is a video about "How sexy you are according to astrology" by astrolada.
https://www.youtube.com/watch?v=nF6B0wD2OGo&t=257s
This is also a general over view of how planets look like but shorter.
https://www.youtube.com/watch?v=6Ikn2hBmltU
This is general overview how planets will look like.
Wanted to add that lunar mansions (nakshatras) also affect appearance and sex appeal.