That's not even what a tariff is. Tariffs don't go on retailers
But indirectly it will be, because the tariff on the product from country X Y or Z will apply no matter who sells it, Amazon or otherwise. And who cares if it is Amazon selling it, or store123456 on ebay, or "cheapjunk4u.com"?

Trump threatens Mattel with 100% tariffs as doll fallout escalates
Mattel CEO said tariffs will not increase toy production inside the US

Lol, remember this? I told you he could call it whatever he wants, you made fun of me and yet here we are.