A young boy with close-cropped hair, wearing a red robe, is holding a black kettle as someone is about to pour something in it.
a small boy holds a kettle that will soon be filled with salsa
Just because someone is about to pour something in the kettle does not mean that the kettle will soon be filled; nor does it mean that the something about to be poured is salsa.
We have no idea if they are filling it with salsa, it could be filled with anything.
You can not infer the boy is small.