start with 'expressionist painting of ...' and whatever is your subject matter
Having trained on this style for both SDXL and Flux, this is by far my favorite LoRA in this vein. Trained on the work of my favorite German Expressionists (Marc Chagall, Egon Schiele, etc) the output is a simplified drawing style with expressive, fluid brushwork and a muted earth-tones color palette.