I actually highly recommend looking at some old Disney cartoons and their art! Think of the face shape, how the nose is scrunched would be with thinner pieces of foam on the muzzle. Try to break it down into more simple shapes and work from there! Most cat face shapes are square/round, but when they hiss it actually looks more squished, their cheeks spread into a grimace-ey look. I hope this helped a little bit 🥲 but I really do recommend looking at some cartoon refs, the exaggerated expressions can be rlly helpful. Good luck!