what type of chemical reaction is this CH4 + 2O2 → CO2 + 2H2O

The given chemical equation is a combustion reaction.

I call it oxidation.

Yes, you are correct. Another term for this type of chemical reaction is oxidation. Specifically, it is the oxidation of methane (CH4) in the presence of oxygen (O2) to produce carbon dioxide (CO2) and water (H2O).