What's the foreign policy goal of the blanket tariffs across every country? Hint: There isn't one.
Its stated goals are revenue generation (Congress's job) and domestic economic development (not foreign policy)
As of blanket tariffs across all countries not being foreign policy I tend to disagree, it’s a policy of protectionism. I just don’t think this particular foreign policy falls under executive oversight, and should originate in Congress.
The case when tariffs fall under foreign policy is only when used to achieve a foreign policy objective only in response to an "unusual and extraordinary threat".
Taxes can be for raising revenue, but they can also function as clubs for changing behavior. Cigarette taxes, for example, have the purpose of deterring people from smoking.
Tariffs similarly can serve as clubs against foreign countries. You might have a tariff on China to get them to change their domestic policies. In that capacity, the tariff is functioning as a foreign policy tool; the revenue generation is incidental.
Hell we don't even need to go that far afield: your logic implies all taxes are foreign policy, as they all affect foreign trade.