SO2 is not likely to be ionic.
An ionic bond is most commonly formed between a metal and a non-metal.
K (potassium) and Br (bromine) are a metal and non-metal pair.
Al (aluminum) and Cl (chlorine) are a metal and non-metal pair.
S (sulfur) and O (oxygen) are both non-metals, and likely formed a covalent bond instead of an ionic bond, which is common for two non-metals.