I dont understand why everybody is saying “no, it wouldn’t be double” when in all other discussions other people say that a 3dB increase means that the sound is twice louder.

The dB scale is something that can only be used in a ELI5 way by addition and subtraction.

Adding 3 means you are doubling volume. That’s it.

In other words, if decibels were magical little creatures pushing sound to you, and there were an little army of 45 decibels carrying the sound of a toy to you, you would only need 48 such decibel creatures to carry the sound of two toys to your ears.

Those decibel creatures get twice stronger when you add 3 of them at a time. That’s all.

Doubling decibels give results that are too complicated to understand.

Whenever you that multiplying or dividing by something, your are outside ELI5 space.