After coming in third on 2018’s “America’s Next Top Model,” plus-size contestant Khrystyana Kazakova was thrilled to land a contract with a top-tier agency. But the feeling didn’t last long: The size 8 beauty was soon informed that she wasn’t “big enough” to net the most competitive jobs.

“I was told that if I gained more weight, I would make more money,” says the 34-year-old blonde. So the Siberian-born Brooklyn resident changed up her diet and exercise routine, replacing cardio workouts with weightlifting and squats, and indulging in fatty, protein-heavy meals.

Within two months, she gained 10 pounds, but not the way the agency envisioned. “They want you to have an hourglass shape,” she says. “Before firing me, [they] implied that I looked bloated.”

As the market for plus or “curve” models expands, a new impossible beauty standard is emerging. While Rihanna’s Savage X Fenty, Reformation and a few other brands are praised for their inclusive sizing, models say that behind the scenes, the pressure to be the “right” kind of plus is greater than ever. They say agents and clients alike are seeking a specific body type: the chiseled hourglass figure, embodied by Kim Kardashian and Jennifer Lopez.

“They want you to have small arms, a beautiful jawline, a slim waist, but you can have all the boobs, ass and thighs you want,” says 22-year-old curve model Allison Owens, who lives in Bushwick.

Chelsea Bonner, a former model and founder of Bella management, which reps Robyn Lawley, the Sports Illustrated Swimsuit Issue’s first curve model, says plus-size modeling has become an industry with clout.

But as positive as that is, Bonner says, this new industry is plagued by double standards.

“We’ve created an avatar of what is allowed to be plus-size,” she says. “So you’re allowed to be curvy as long as you have a really tiny waist and no cellulite.”

She says the issue is more pronounced for the models she calls “in-betweenies,” those stuck between sizes 10 and 12. “Those models feel like they have to bulk up or keep weight on in order to work,” Bonner says, “or otherwise starve themselves down to fit into a sample.”

Madeleine Ours, who began modeling two years ago as a size 10, says that’s been her experience.

“The standards for beauty are just as rigorous for plus-size models,” says the 26-year-old, who lives in Brooklyn and has worked for high-end brands such as Mara Hoffman as well as more mainstream ones, including Target and Kohl’s. “There’s times where I’m like, ‘Should I lose or gain weight?’ I always wonder what the industry is wanting next. I don’t know what’s going to be the trendiest size.”

The brunette bombshell is currently a size 14, and says she’s booking more jobs than ever. But she says it’s taken work to stay in the most marketable shape. “I eat a low-carb diet and do interval training, weights and cardio with my trainer,” Ours says. “People joke that straight-size models have to diet and we don’t work as hard, but it’s a big misconception.”

And the work doesn’t stop at the gym. For those curve models who fall outside of the ideal size window — sizes 14 to 16 — booking gigs means tirelessly promoting themselves on social media.

Atlanta-based stunner Alexus Rackley has been modeling for two years, landing deals with Nordstrom and Amazon. As a size 18, Rackley is on the bigger end of the plus-size model spectrum, which she says comes with its own set of issues.

“I’ve been to castings where I’m too big or too curvy and I don’t get that booking,” the 25-year-old says. “I had to put myself out there and grind and promote myself as a model.” She says racking up more than 53,000 Instagram followers gave her a crucial boost: “Otherwise, [clients] don’t look for people my size.”

Molly Tellekson also struggles to find her place in the modeling world.

The Crown Heights resident, now 26, began modeling in 2016. An athletic vegan, she finds herself in that difficult “in-betweeny” category.

And so, to keep her career afloat, she uses padding to fill out plus-size samples. Padding is a trade secret in the plus-modeling world, a standard way to achieve that hourglass ideal.

“For a while, I refused to buy padding, but I was losing out on so many jobs, I sold out and bought it,” Tellekson says.

But she says padding makes her feel like a fraud: “It’s not even just Photoshop fake. I have literal pieces of foam stuffed into my Spanx.”

At one shoot, she used padding to fill out some size 14 and 16 samples, but she’s unhappy with the message those images send.

“My neck and collarbones are the size that I am, and below that is pretty much a fat suit,” Tellekson says. “That’s an unrealistic standard of beauty for girls who want to buy these clothes. If I was a size 16 woman looking to buy [that] dress, I’d think, ‘Why isn’t my neck that thin?’ ”

Other women are resorting to more invasive — and permanent — body modifications, such as tummy tucks. Former “America’s Next Top Model” finalist Kazakova, now affiliated with the One Management agency, says she won’t be one of them.

“I said no to tummy tucks, I said no to cellulite reduction procedures and I said no to Botox, for now,” she says. “I’m not against those things, it’s just something I chose. Because I know that people look up to me.”

Kazakova’s 343,000 followers on Instagram are supportive — to an extent. She says they’re also quick to criticize if she’s not “accurately” representing the plus-size community.

“God forbid I look thinner than the day before. I get all sorts of messages and DMs,” says Kazakova, who founded the Real Catwalk, which produces guerilla fashion shows that promote body diversity. “I’ve had commenters say, ‘Oh, you’re not part of us anymore, you’re not body positive anymore.’ ”

For her part, Tellekson applauds the brands that seem truly size-inclusive — Universal Standard, Chromat and Girlfriend Collective among them. While other brands simply use curve models as a kind of “tokenism,” Tellekson says these companies don’t distinguish between straight and plus sizes in their collections. They also leave model photos unretouched and, in the case of Universal Standard, supply clothes up to a size 40.

“I do think the fashion industry is moving in the right direction,” she says. “It’s a cool thing that size 16, 18, 20 girls are represented, because those women haven’t been represented in the fashion industry at all until now.”