Misunderstanding: the power is the only factor affecting brightness. The higher the power,the greater the brightness
The brightness can be reflected by lumens and The lumen(lm)=The light effect(lm/w) * The power(w)(ex:100lm=100lm/w * 1w )
So the power is not the only factor affecting brightness and the light effect is also important.
The light effect higher, the less power required for the same brightness.
The more power, the higher brightness under the same light effect.