I was talking about the oposite of what you talk (Limiter); in the example I wanted to raise the wave to 0db (maybe you are confused because in the ‘Waveform’ view Audacity shows ‘0’ in the center [there’s a petition* -which I agree with- to use db also in this linear view, with 0 at the borders, like eg in Cooledit]) through an improved Envelope Tool.
And I know there are other ways to raise a low wave eg. with Compressor, I want the convenience of visual manipulation of the Waveform with the Envelope Tool, more precise and with more range than currently (to raise or lower the wave, whatever, 0db was just the example).
https://forum.audacityteam.org/t/need-a-vertical-with-focus-on-range-from-0-to-10-db/51598/1