The best way to predict the future is to study the past.
Trump is repeating the policies of the 1930's not a particularly good idea.
I've just looked according to Trump the UK imposes 20% tariffs on goods from America that is a lie.
What he is refering to is the 20% VAT that is in effect a sales tax that is imposed on just about everything sold in the Uk no matter where it originates from even domestically produced.
The EU has VAT as well Trump is obviously not being truthful with the figures or he's too thick to understand which I doubt, more like he's playing to the MAGA faithful and those either too stupid to understand or just accept everything he says as gospel
When other countries retaliate and impose their own tariffs things are going to get very expensive in America of course that also means a lot more money going to the treasury collected from ordinary Americans that are paying the higher tariff prices.
The result of all that will enable Trump to give massive tax breaks to the millionaires and billionaires that bankrolled him.