The Plus size market is growing and models of all sizes are working as models.
If you want to model and you are of plus size here are some tips I found from
Plus-size models are models who are hired to represent the plus-size woman. They generally range in size from a missy 8 all the way up to a size 32W and participate in a variety of modeling jobs including print work, runway shows, and fit or informal modeling.
Plus-size models have many of the same requirements "straight size" models do. They are usually tall (5'8" to 6'0"), have a beautiful face, great bone structure, clear skin, a gorgeous smile, and a well proportioned body. They often find work from their mid-teens all the way through middle age and work in markets all over the US and around the world.
Here are some agencies:
Wilhelmina Models - ten/20 division
Ford Models New York
Also commercial print modeling agencies:
Model Service Agency
Click (plus size)