I stood in a changing room once with a pair of regular jeans pooling over my trainers, already folded into three thick cuffs, and thought, this is ridiculous, I am a grown woman doing origami with denim just to leave the house. Then I tried a petite pair in the same style and the hem sat exactly where it should, no bunching at the ankle, no dragging on the ground getting wet and grey at the back. That was the moment it clicked. It is not a smaller version of the same jean, it is a differently proportioned one, and for anyone under about five foot four it changes how every pair sits.
Before buying, check where the rise sits and where the leg starts narrowing, because petite ranges handle this differently from brand to brand. Some just chop length off the bottom of the regular pattern, which throws the knee bend and the taper out, so the narrowest part of the leg ends up mid calf instead of at the ankle. The better ones redraft the whole pattern, shorter rise, shorter distance between crotch and knee, not just a shorter hem. Look at the inside leg measurement given in the product details rather than trusting the word petite on its own, and check the rise too if you're short waisted as well as short legged, because plenty of us are both and a petite leg with a regular rise just moves the problem up to your ribs.
The honest limit is that petite sizing solves length and proportion, not shape. It will not fix a cut that doesn't suit your hips or thighs, and a cheap pair will still gape at the waistband or go baggy at the knee by lunchtime no matter how perfectly short the leg is. Petite also tends to mean a narrower overall fit, so if you carry any weight on your thighs or calves, a style that's petite and skinny can feel like a sausage casing rather than a flattering line. That's not the length doing its job, that's just a cut that was never going to work for your shape.
Don't pair a true petite fit with anything that visually shortens you further, a long oversized coat that swallows the proportion you just fixed, or chunky ankle boots with a thick sole that eat back the inch of leg length you gained. A fitted jacket and a low vamp shoe keep the whole point of buying them in the first place.
Best for anyone shorter in the leg who's tired of hems doing the work a tailor should be doing.