Create a concept art illustration of an elderly, plump witch in three different poses, depicted in a whimsical, caricature style. The witch should have a large, spherical body, with exaggerated, rounded features that emphasize her chubby and endearing appearance. Her form should convey a sense of fullness and softness, with her round belly and plump limbs being key characteristics. She holds a crooked staff and is accompanied by a mystical bird, both designed to complement her rotund, caricatured style. The witch's outfit and accessories should be rich in shades of violet, from deep purples to soft lavenders, adding depth and vibrancy to her character. The overall vibe should be playful and magical, with her plump figure, bird, and staff adding to her charming, cartoonish appeal. The background should be minimalistic, allowing her vibrant design to stand out.