Class(es) for animating objects on a canvas
This is really cool! I do have a few small tips though.

First off, rather than creating an entire function, in this case, config, that returns configuration data, I'd store it as a public getter, like this:

class Wave {
  static get CONFIG() {
    const waveBaseLength = 5;
    return {
      color: '#4F5E5B',
      waveLengths: [waveBaseLength, waveBaseLength * 7, waveBaseLength * 15],
      velocity: 5
    }
  }
}


Using this, you can do stuff like Wave.CONFIG.color, and drop the un-needed parentheses.

Finally, you have a few, not so great variable names. A few include l and n. Names like these should be expanded for clarity and readability.