It does depend on the size and strength of the child as well as age, confidence and 'nous' when it comes to handling pans of boiling water and kettles, of course. My DD being the child of a shortarse mother is at 12 still not entirely comfortabe with the kettle and can only use the bottom (small) oven not the top one.
(I can cut bread beautifully, even freshly homemade loaves. Of course slices of that are supposed to be about an inch thick
)