Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
This is from the Constitution (see https://constitution.congress.gov/constitution/amendment-1/ ). The First Amendment is in three parts, one of which is devoted to freedom of speech. The other two concern the prohibition of establishing religion and allowing its citizens to petition (read: protest) for a “redress of grievances.” While he was president Trump broke all three quite consistently and quite hard. The establishment of religion was in my opinion the worst, with the allowance of evangelical Christians into the White House for public “laying on of hands” and very public praying, for which Christ himself spoke of in his Sermon on the Mount (Matthew 6:5):
And when thou prayest, thou shalt not be as the hypocrites are: for they love to pray standing in the synagogues and in the corners of the streets, that they may be seen of men. Verily I say unto you, They have their reward.
Now Trump wants to make a big deal out of his being banned from all the social media platforms of consequence. And that’s where Trump shows his total ignorance of the First Amendment. When the First Amendment talks about “abridging freedom of speech,” it’s talking about Congress, meaning the federal government, from abridging freedom of speech. The government doesn’t own any of the platforms, and makes no attempt to regulate them (although regulation may come sooner than later due to documented monopolistic practices having nothing to do with free speech). Trump is pissed because a lot of people got tired of his endless lying and what it eventually led to, i.e. January 6th, which led to his being booted off those social media platforms. Or, to put it rather succinctly: