Here’s a pure English prompt for a cold ancient-style immortal-cultivation big-breasted mature sister:

Cold and elegant ancient Chinese immortal cultivator, mature御姐, tall and slender figure, huge breasts, fair and cold skin, distant and indifferent eyes, aloof temperament, elegant Hanfu with flowing silk ribbons, long black hair, ethereal immortal aura, clean white background, soft lighting, high detail, realistic rendering, elegant and mysterious, ancient fantasy style, dignified and cold beauty, graceful posture, delicate facial features, noble and untouchable atmosphere
naked