Tekken 8 muscle striation technique

Hey folks, check this out! Just caught a glimpse of the muscle detail in Tekken 8 running on Unreal Engine 5, and I’m mind-blown. How do you think they pulled off those muscle striations? I’m guessing normals played a role, but it looks so razor-sharp and clean—makes me wonder if they threw some texturing wizardry into the mix. What’s your take on it?