Lumens, not assumptions
Lumens describe visible light output. Wattage describes electrical input and does not allow a reliable brightness comparison across LED modules, replaceable bulbs and fan motors.
Standard output
Each product page states a FIFTH & BEAM standard lumen configuration for the selected size. Larger formats generally receive a higher standard output when the light source allows it. That value is intended as an understandable default rather than a laboratory claim about every possible custom configuration.
When you need more light
Use more than one light source or request a higher-output compatible configuration for large rooms, dark finishes, tall ceilings or task-heavy spaces. Dimming changes usable output; color temperature changes appearance but is not itself a measure of brightness.