There’s a de-esser here:
https://forum.audacityteam.org/t/updated-de-clicker-and-new-de-esser-for-speech/34283/1
Note that there are two plugins: DeClicker and DeEsser. You want the DeEsser.
Be sure to read the first couple of pages of that thread, which includes installation instructions and some feedback on using it.
– Bill