SD3Transformer2DModel  
The Transformer model introduced in Stable Diffusion 3.  
Reference: https://arxiv.org/abs/2403.03206  
Parameters:
sample_size (`int`): The width of the latent images. This is fixed during training since
it is used to learn a number of position embeddings.
patch_size (`int`): Patch size to turn the input data into small patches.
in_channels (`int`, *optional*, defaults to 16): The number of channels in the input.