1. get a burner phone 2. get a cheap laptop and put linux on it 3. setup a non-domestic vpn on the device 4. don't use this equipment with any accounts tied to use 5. use the burner phone via vpn in order to establish social media accounts. 6. use these social media accounts over vpn to make your statements...
This often doesn't work or is much more difficult than it sounds.
Many social networks don't allow anonymity and they detect attempts to stay anonymous.
In an extreme case your account might be blocked soon after creation and you might be asked to upload a photo or ID scan.