Quite often I see how people upload photos with a fairly high resolution (1024x3120) and more. For me, 1024x1024 is the limit. Tell me how to do it. Thank you
use hires fix
You probably can't get that high without getting a gpu with more vram. If you wanna try pushing your limit a little more you can install webui extensions for VAE tiling and token merging. I have only 4GB of vram and my max is 768x1152 with VAE tiling and token merging and rendering only TWO images at a time. Can't go up to 3 or more batch size. And still sometimes I will randomly get out of memory errors and have to restart Stable Diffusion.
Highres fix isn't for simply reaching a higher resolution, it's for re-rendering already rendered lower res images. Since many models can't properly render straight to higher res without making some really bad looking images they need a base image made first at typically 512x512 or 512x768. Stable Diffusion v2 based models would be 768x768.
Since I have a slow GPU I don't use the highres fix checkbox and instead find an image I mostly like first and then take it to IMG2IMG to manually do the highres fix.
Anyway, good luck. Hopefully you can get up to 1024x1536.
Edit: Also try xformers