He literally said he was gonna:

"Trump vows massive new tariffs if elected, risking global economic war"

https://www.washingtonpost.com/business/2023/08/22/trump-tra...

(https://archive.is/20231125045858/https://www.washingtonpost...)

EDIT - Found this after my post, a MUCH better "he said it":

https://www.donaldjtrump.com/agenda47/agenda47-president-tru...