Could I use iphone applecare+ from other country?

Apple Care might be limited to the country of purchase:

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Apple may restrict Hardware Service and ADH Services to the country where the Covered Equipment was originally purchased.

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copied from:

Legal - Apple Care+

No.

Not just repair, but replace as well. Apple will NOT replace a phone purchased in another country because they won't have that model phone in stock in a different country.

Apple will check your device online, to see, if it has any damage, before you can buy Apple Care plus.

When they diagnose the device, they will recognize, that the phone has not been sold in the US, and you might not be able to buy the Apple Care plan.

Each iPhone is made for the use in the country where it has been sold, an so is the hardware inside the phone.

Differieren countries require different hardware, for example if it comes to using LTE or other network features. So, if you are having hardware issues with your device in the US, Apple might not be able to repair your phone, due to the missing hardware spare parts.

That means, that Apple will try to repair your phone by using parts, that are available in the country you are staying in, at the time of the damage. Or they will replace the whole unit with an iPhone from that country, to make sure, you are having at least a functional device for this region.