Typically generative models, particularly diffusion models like Imagen 3, are easily architected to support several vectors toward the latent space of the model. It is not open source so there might be an architectural reason I cannot see, but I don't think the public interface to the model should suggest its capabilities -- it is uncommon for image to image not to be supported in open source image generation models, for example. However, there are definite legal reasons not to provide such a vector in a public facing model like Imagen 3.