Redirect any server_name to the first one defined

nginx-redirect-to-first-servername.conf

server {
  listen 80;
  listen [::]:80;
  server_name example.com 1.example.com;

  # Redirect all HTTP links to the matching HTTPS page
  location / {
    return 301 https://$host$request_uri;
  }
}

server {
  server_name example.com 1.example.com;
  listen 443 ssl http2 ;

  ssl_certificate /etc/nginx/ssl/live/example.com/fullchain.pem;
  ssl_certificate_key /etc/nginx/ssl/live/example.com/privkey.pem;
  ssl_trusted_certificate /etc/nginx/ssl/live/example.com/chain.pem;

  # Forward to the first Server Name
  # https://stackoverflow.com/a/40411590
  if ($host != $server_name) {
    rewrite ^/(.*) $scheme://$server_name/$1 permanent;
  }

  location / {
    ...
  }
}