How does watt affect the quality of sound in a led bluetooth speaker?

Watts are merely a unit for describing the output power of an led bluetooth speaker, in other words how efficiently it is able to throw the sound out to the listener, and fill a space. What you hear will depend on how you listen, how far you are from the led bluetooth speaker, and how far up you have turned the volume control.

Any difference in quality from a live performance or from another audio system of the same size and type is due to other factors than mere output power. The human mind, however, may make an interpretation regarding quality based on impression, personal preference or prejudice, or other circumstances connected with the listening event. This is true of any led bluetooth speaker setup, regardless of whether or not it is led bluetooth speaker.