How much wattage should an LED ceiling lamp for a room have?

Question

LEDs

Good evening!
Tell me, what power should an LED ceiling lamp have for a typical 6x3m average room?
The choice fell on

Xiaomi Mijia Ceiling Lamp (350 мм) 
Обслуживаемая площадь: 8-15 м²
Мощность освещения: 24 W

It turns out that it will illuminate 15m at maximum power, which is not good?

There's another one, but it's huge.

Обслуживаемая площадь: 15-25 м²
Мощность освещения: 45 W

Answer 1

The LED lamp has a so-called light scattering angle.
Next, there is the concept of luminous flux. And then something interesting pops up. For the same power, the amount of luminous flux can be different, and this value can differ significantly.
You are also interested in a different light value - the level of illumination.
Now, knowing the angle of light scattering, we can calculate the area of ​​the light spot. Knowing this area and the luminous flux, you can find the illumination. For accurate calculations, you also need to know the geometry of the room, the furniture in the room, their reflective abilities.
So, a lot of vague ones to answer your question.