How to set default server locations for account (for Key Management Service)

AWS KMS supports multi-Region keys, which are AWS KMS keys in different AWS Regions that can be used interchangeably – as though you had the same key in multiple Regions.

https://docs.aws.amazon.com/kms/latest/developerguide/multi-region-keys-overview.html

You can't select a specific country but you can select specific AWS Regions where you want to use the service within. Check out this doc on how to select your default region: https://docs.aws.amazon.com/awsconsolehelpdocs/latest/gsg/select-region.html

Once set, any key you create will be created within that region.