I don’t think any president, even the famously erudite Obama, literally sits down and writes a speech of any importance all by themselves without any editing or input from speechwriters whatsoever.
Nevertheless, you can detect patterns in tone and such that suggest to what extent the President himself was personally involved in the speechwriting process.
For example: Obama’s inauguration speeches were reasonably comparable to the tone he displayed when speaking at a rally or extemporaneously, though a notch loftier.
Trump’s inauguration speech, however, was totally different in tone from the combative off-the-cuff remarks he typically gives at rallies or in his personal tweets (which I have read he actually dictates, at least typically)
So: Some similarities in content, but a whole lot more dignified and conciliatory than he typically is.
I’m not saying Trump ever says stuff he literally disagrees with — but when someone else writes his stuff it is pretty obvious.
Trump’s brand is partisan combativeness pure and simple and that was my overall point. You can’t blame this all on CNN.