The First Amendment and the Indictment of Donald Trump

The indictment centers on Trump allegedly knowingly spreading and acting on false claims about the 2020 election results. How much does the first amendment play into Trump's argument? It plays a great deal into it because let's put aside the monumental task that Smith would have in terms of proving that Trump knew what he was saying was false, which I think is going to be a tough row for him to hoe.