Build an nginx server block

server {
    listen 80;
    listen [::]:80;
    server_name example.com;
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name example.com;
    root /var/www/html;
    index index.html;

    location ~ ^/old/(.*)$ {
        return 301 /new/$1;
    }

    location /api/ {
        proxy_pass http://localhost:3000;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}