Here's the deal - models are taught how to pose, and when plus models are taught how to pose it involves hypersexualization and slimming techniques.
Your favorite model for Forever21 or rue107 has been taught that to be seen as beautiful on camera she must pop her hips/booty, suck in her stomach (under layers of shapewear already), throw her breasts forward and up, lift her chin so there is no fat to be seen, and then "make love to the camera." No shit, people still use that line.
This isn't the models fault. This is years of the industry telling us that we can use fat women in marketing ONLY if they appear a certain way. Have you browsed a "curve" model board recently? Did you know there are model boards you can browse? There are, and most of the models look very much alike. You have the girl-next-door white girls with the pouty face (basically what has been your most popular porn category for decades), the mixed race girls that are ethnically ambiguous and leave you going "I can't put my finger on her ethnicity but that doesn't bother me because I can identify she is not white." You will also see the dark skinned black girl, but like only one or two of them. Too many black girls and the agency blows up or something. I don't know. Optional for New York boards: the one or two "weird" models but they aren't as weird looking as the weird thin models because fat women are still gross so they have to be appealing in some way.
All of this is based on the idea of using women's bodies to sell what is acceptable in society. Fat women have been told that in this industry we have to be sexy in order to accomplish this task. Even fat women looking at a fat model will say "oh she looks sexy, I want that." Why? Because we are teaching women that they must be sexy in order to be seen as a worthy human deserving of basic human rights.
Do we teach confidence? No. Do we teach self awareness? No. Do we teach self love without it caked in weight loss? No. But we do teach sexy. We teach sexy by only showing sexy models to the masses. We teach sexy by telling models they are only pretty when they are sexy. And only pretty models are good models. WRONG.
Ugly humans by society's standards are STILL HUMANS. Why can't ugly be seen as equal to beautiful? Ugly does not equal less worthy, it is simply the visual representation which society finds unattractive. Society is acting as one group in this conversation, not as separate people or groups, or even demographics. Ugly people and beautiful people are all humans, and why should someone's visual appearance mean they get less in life? Moreover, why does a fat person have to be seen as sexy in order to be seen as beautiful?
The plus model's default is "sexy." It just is. It is the way models get jobs, it is how they get popular, it is how others models see them. Often, it is very difficult for models to even see this is happening in their own careers, but it is. Hypersexualization can be fixed, but models need to start breaking down barriers. Stop waiting for clients to do it. Stop waiting for agents to do it. Book a photographer and have them push you out of sexy and into something that echoes human emotion.