I have a similar body shape to jennie but i am wider and taller. I have a pretty small waist with really narrow hips and over all pretty slim especially towards the calves. I also have "thicker" knees like her. But I do have shorter legs than her and a butt that does not suit the size of my legs/pants. Watching her outfits over the years, I am able to realize you can take inspiration from idols on what they wear and apply it to your own wardrobe that matches your body type better. you can really tell that she wears what is right for her body and emphasizes in a right way and as a result she sometimes gets the slim hourglass look. I was able to learn alot from her outfits so this is pretty obvious but I think its good for people to find similarities within certain areas and wear similar things to emphasize or cover them.
Pants – HIGH WAISTED no matter what. The slim waist will be the emphasis point and covers the narrow hips. As a result you may get the illusion of the "hourglass" silhouette thanks to the thighs area or the hip bones
-thicker the better. If you like hip dips/ or the narrow hip look this isn't the tip. This helps fill out the narrow ness of the hip and extends the body sideways below the waist. It will also help lengthen/straighten out how your legs look( if they are knocked or bowed.) Maybe choose pants that have accessories or beading on the sides or all aroud that make the hip area look bigger
-HIP PADS +denim/thicker material pants or shorts. Tbh idk many people who use this on a everyday base. It's just used more in kpop. If we remember jennies iconic grey denim skinny jean look in her concerts, she wore hip pads then and it looked really natural and also gave her an extra point to her look. She wore them again sometime at another event with black pants where she wore a one shoulder top. Those were slightly obvious because of how tight and thin the material of the pants were. Her looks on either of those days may be more ideal than when she wore did the head to toe denim look at the air port where her narrow hips were emphasized
-Flared shorts. Once again emphasizing the waist and giving the wider hip illusion following the shape of the thighs not the hips
-THIN SHORTS THAT ARE NOT FITTED. This kinda goes against what I said before but often with thin, harder fabrics that don't stick like leggings, You can get a really nice slim look. This is because the shorts start from the waist and rounds out in the place of wear the thigh leads once again creating this triangle mid section look that gives a fuller illusion. Jennie wears these alot in most of her iconic stage outfits
Shoulders jennie is blessed with striaght shoulders that make any top look elegant and chic. At the same time her shoulders are definitely not narrow and in this case it helps her with her styling. -wear straight shoulder shirts or shirts that are thicker or hav horizontal stripes. This tip works better with crop tops. You are able to emphasize the waist, neck, and face. Just make sure you don't over compensate with the shoulders making your legs look smaller -tshirts that have the sleeve go down more on the upper arm. This actually prevents the sloped shoulder look
Shirts I may be wrong but I would assume Jennie is a B or a C cup. Looks different depending on what shirt or bra she is wearing time to time. The only tip in general is if you are as skinny as someone in blackpink or a female kpop idol in general, avoid any over pushed up bras. It may look unnatural and unless you are going for the P shape, the look may not be the ideal for you. However if you do want to emphasize a bust, go for it. Everything is a look in it's own way.
Dresses/Skirts -SINCHED WAIST, this is you biggest asset to make you look elongated -A line -if you do go for a tight dress make sure the dress isn't too long and maybe wear thicker shorts under neath . Or find a thicker material dress -appropriately shorter – there are some outfits where the narrow hips or a wider waist actually make the dress look better on you so before avoiding anything, try it out. You are bound to look amazing in it