This Prebuilt Deployment example demonstrates how to use configure routing rules based on which domain name was requested, when using the Build Output API.
https://build-output-api-wildcard.vercel.sh
The "wildcards" configuration in the .vercel/output/config.json file allows you to configure
any number of domain names (or sub-domains) that point to the same Deployment to route to specific pages based on the domain
name that is being requested. The most common use-case for this is to offer localized versions of your content based on the domain name.
When a matching domain name is requested that is configured in the "wildcards" configuration, the "value" is passed to the
routing configuration and can be referrenced by using the $wildcard placeholder. This allows you to route to specific
static files based on filename (like in this example), or to append that wildcard value as a query-string parameter for use
in your Edge and/or Serverless Functions.