About Domain Redirection to WWW or Non-WWW

server {
    listen 443 ssl;
    server_name example.com www.example.com;
    charset utf-8;

    if ($host ~ ^(?!www\.)(?<domain>.+)$) {
        return 301 $scheme://www.$domain$request_uri;
    }

    # SSL certificate and other directives...

    root /var/www/html;
    index index.html;
}

server{
    listen 80;
    server_name example.com www.example.com;

    location /.well-known/acme-challenge {
        root /var/www/letsencrypt;
        try_files $uri $uri/ =404;
    }

    location / {
        return 301 https://$server_name$request_uri;
    }
}

if ($host ~ ^www\.(?<domain>.+)$) {
    return 301 $scheme://$domain$request_uri;
}