Man, reddit users sure don't change, do they? DAE have this incredibly popular opinion? Has anyone thought of this very obvious idea?
Teasing aside, you should be able to find multiple options on how to do so with a simple google search, or a search of old posts in this very community. Terms like comment scrubber or account wiper.
This was incredibly common during the first big "exodus" of reddit users when they started cutting off third party api access, killing nearly every third party app and almost all moderation tools.
I'm honestly shocked you haven't seen any of those "replaced" comments yet. They're pretty common in any reddit thread more than a few months old that shows up in google search results.
It will most likely get you banned before you replace all of your comments, and if you somehow have a popular enough account where the reddit employee admins care, they can revert your changes after banning you. They did this with a large number of accounts during "the exodus", where people went back a week later to find their comments restored and they couldn't log back in to do antthing about it. Some users attempted to get their comments removed after that via GDPR requests, but I'm not sure if anyone reported back on if that worked or not.