kersploosh

Plemmy is a Python library that might be helpful for building a bot: https://github.com/Fedihosting-Foundation/plemmy

Also this Lemmy API reference: https://lemmy.readme.io/reference/post_community-ban-user

Pick a few Lemmy instances and look at their instance block lists. Compare the lists and pick out the commonly blocked instances. Within that select group you will find some radical free speech places where anything goes. Be warned that they tend to be cesspits.