This is a lora for Flux 2 Klein 9B Edit that takes in an image of a guy and makes him more muscular. I trained it on the base model, not the distilled, so the effect looks best on the base 9B model and more subdued on 9B distilled.

I just used the default Flux 2 Klein 9B Edit Base ComfyUi workflow and added the lora load inside the subgraph. Your prompt can just be the single term: muscle_morph , although I've noticed it tends to like to make the person shirtless, which you may or may not want. You can add more to the prompt to cue it in that you want the clothing to remain but refitted.