An NPK complex can be used if the dose asks for

NPK complex is a solid three nutrient fertilizer in a single granule that is produced via chemical or physical processes but excluding bulk blends. And normal NPK is a complex fertilizer that contains all three major nutrients 10% Nitrogen, 26% Phosphorous and 26% Potash.
As both are the same, thus, NPK complex can be used if NPK dose is required.