"….TRIUMPHAL ARCH, but it will now ~~and~~ be, by far, the greatest of them all! Thank you for your attention to this matter. President DONALD J. Trump"
"And" should be "Be". That's all I'd do.
You can additionally put the "and" before "by far".
"….TRIUMPHAL ARCH, but it will now be, and by far, the greatest of them all! Thank you for your attention to this matter. President DONALD J. Trump"