There are multiple workflows for each:
txt2img
img2img
inpaint
txt2img controlnet
img2img controlnet
IPAdapter
They all have additional upscale nodes, which are disabled by default.
Just switch checkpoints if you want to use SD1.5.
Pony or Illutrious is SDXL fine-tuned, so of course it works with this workflow.
The version is controlled in: