First, spoof your IP address.
Then, start with Facebook. Create a realistic looking account, preferably with bots for friends, and start sharing and commenting on hateful groups' posts. They'll come out of the woodwork and if you play your cards right you get invited to Discord servers and shit like that where the really heinous stuff happens.
Then, after taking months of screenshots and compiling all the data you can, you turn it over to Unicorn Riot or a similar group and watch the fireworks.