There are no tarriffs being applied on digital services. That's obviously intentional considering how much soft power those services exert on countries the USA wants to maintain an outsized influence over.
Tarriffs are a tax on imports to the US applied by the US government.
You can't tarriff selling a service overseas, in fact since AWS in other countries is a locally incorporated entity you can't even meaningfully demand they charge more AWS in the UK is a separate corporation incorporated and taxed under UK law, for example.
How would tarrifs be applied on digital services?
Tarriffs are a tax on imports to the US applied by the US government.
You can't tarriff selling a service overseas, in fact since AWS in other countries is a locally incorporated entity you can't even meaningfully demand they charge more AWS in the UK is a separate corporation incorporated and taxed under UK law, for example.