@yulac
For a fade effect that supports preset fade shapes I’d recommend “FadeInOut-02.ny” by billw58 https://forum.audacityteam.org/t/simplified-flexible-nyquist-fade-in-and-out-effect/16042/3
This effect does not support “partial” fades. The fade is always either “Fade In” (from silence to the original level), or “Fade Out” (from the original level to silence).