This is a way of refining and rebuilding an initial image using a set of Layers, not as good as photoshop layers but still pretty effective. It's fairly advanced but you can look at earlier videos to get up to speed. I'm using Flux dev but it will work fine with smaller versions of Flux as well. Workflow is below, just drag and drop the PNG into Comfy. Or you can download this json file:
Hide player controls
Hide resume playing