Comment by vunderba

It depends on the model. Diffusion models, which are among the more popular approaches, are typically trained at a specific image resolution.

For example, SDXL was trained on 1MP images, which is why if you try to generate images much larger than 1024×1024 without using techniques like high-res fixes or image-to-image on specific regions, you quickly end up with Cthulhu nightmare fuel.