I’m pretty sure an Amish vegan would starve/freeze to death (especially if you consider handmade fabrics growable in the climates they live in or transported without the use of engines or horses), but if one existed, they’d also have to refuse to pay their taxes. They’d also obviously have to be one of the Amish who don’t use modern medical care or all manner of modern technology for work. I’m also not sure how resource intensive Amish tools are- if they have traditional blacksmiths, where do they get the metal?

But really, it depends on your inputs: the quickest/simplest ways to cool the planet would also probably render it unlivable for most humans- there are probably a few ways an AI could generate massive ash clouds that block out enough sunlight to bring the temperature down. In that scenario, there would probably be some humans who survive, but they’d probably be in places with very small and non resource intensive populations, so most of eastern North America is automatically out.