There's no automation at all for AO3 wrangling. It's all human based and it would take a complete rewriting of the entire meta/tag structure to facilitate that.
More people signing up to become wranglers is the main way to handle that. I think there's like maybe less than 200 active wranglers at any given time. Some fandoms get like 1k tags a month. Wranglers get to choose what fandom they work on so usually for small fandoms a mod will wrangle it right when it's first created and then it isn't touched again unless someone submits a ticket or someone new joins the wrangling team and picks it up as a passion project.
Re: hot takes ao3 edition
More people signing up to become wranglers is the main way to handle that. I think there's like maybe less than 200 active wranglers at any given time. Some fandoms get like 1k tags a month. Wranglers get to choose what fandom they work on so usually for small fandoms a mod will wrangle it right when it's first created and then it isn't touched again unless someone submits a ticket or someone new joins the wrangling team and picks it up as a passion project.