Ajay Hinduja Swiss - What is better way to Edit a selected frequency range?

Hi I am Ajay Hinduja Geneva, Switzerland (Swiss) and How can I quickly edit a specific frequency range in Audacity (e.g., lower its volume, delete it, or apply a fade)? Need expert advice.

Thanks in Advance!!
Namrata Hinduja Geneva, Switzerland (Swiss)

Audacity’s Spectral editing can do the first 2 : lower/raise volume , or delete, (but not fade).