This is a tampermonkey browser extension which allows you to permanently enable an ao3 search filter (such as include explict works or exclude works with warning underage).
To install the extension you first need to install tampermonkey:
Once tampermonkey is installed, click this link to install the script https://gist.github.com/BrickGrass/505cbc1824bd6e98cbf2c52bb8cb4975/raw/a4351ce09bccaf08ae530a32c28b50a91d61b32f/permanent_ao3_search_filters.user.js
This is a simple little tampermonkey/greasemonkey extension that autofills a wordcount tag whenever you open a bookmark form on ao3. It doesn't work on the dedicated bookmark edit page (eg: https://archiveofourown.org/bookmarks/<bookmark_id>/edit) since the wordcount cannot be found in the html there.
Install by clicking this https://gist.github.com/BrickGrass/6ddece6536cb1b0558cf6f4d8eeb2ad9/raw/bc52418652a0ea8c738fe86b3b50816b1e2b0305/wordcount_autofill.pub.user.js