One domain hosting global websites

Hello.

Is it correct that WordPress is managed by one EC2 (Lightsail)?
In that case, I think it would be better to set up a CDN such as CloudFront.
By using CloudFront, the nearest edge server responds to delivery requests from clients.
If the edge server does not have a cache, it will go to the origin, but if the edge server has a cache, it will be able to quickly deliver content.
https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/Introduction.html

I would recommend using CloudFront to accelerate the site. Assuming you have more than one Wordpress instance, you can map multiple origins to the TLD, and then use Lambda@Edge to create your path-based routing logic to select the appropriate origin. If all instances of the host contain the same site content, then you dont even need the custom routing or path parts at all.

See:

• How to Accelerate Your WordPress Site with Amazon CloudFront
• Content-based dynamic origin selection with Lambda@Edge. Pay special attention to the example titled Example: Using an origin request trigger to change the origin domain name based on the country header as that seems most relevant to what you need.