This strikes me as incredibly imperialistic. Why should the USA get to decide what the tax rate is for the rest of the world?

You seem to think this will be a hard sell to most countries, where in fact 21% is below Corp Tax for most countries with clout. Most of the EU would be on board, China would be on board, all nuclear powers would be on board...

I doubt either China or Russia would be on board, They might though they would properly ignore it and have many exemptions for State Run businesses or or such things

Start with multilateral agreements, then sanction small jurisdictions that don't comply (e.g. bring the EU, US, Japan, etc on board and negotiate conditions, then impose them on Cayman Islands or Panama).

Those multinationals are following USA tax law! Why sanction the small country when your own country enables the action?

Yes, that is precisely my point.

It shouldn't but it arguably has the diplomatic and economic power to do so.

Hey Henry! See you are still working towards that chestnut.

One people, one government, one leader /s

That user name certainly checks out.

So every city with tax credits. Every county with a tax benefit.

Taxes is not just a federal thing here.