Trying to be anonymous on the Internet is a losers game.
Best you can possibly do is encrypt content with PGP which will raise all sorts of red flags and the sender’s and recipient’s IPs, which can then be used to find names, are still out there.
Best way to communicate would be talking/texting between two throwaway cellphones.
and even those can be tied to time and location by tower triangulation. Get new ones every week or so and pay cash.