Girls, can you help me out? We eat porridge in the morning, but my son…

Girls, can you help me out? We eat porridge in the morning, but my son refuses to eat regular porridge, only eats the baby store-bought one, and refuses everything else. How do I start teaching him? And up to what age can he eat this kind of porridge? ? I added sugar, I don't know. But regular rice as a side dish, buckwheat can be eaten. Oatmeal doesn't even want to try, but he eats the baby version with pleasure ?