Nginx to point to different subdomains

I have a domain (example.com) that I am trying to use subdomains to show different parts of the applications. Right now is all Hosted in AWS.

This is sort of the set up I am trying to go for.

sbx.example.com trn.example.com office.example.com

My nginx conf right now is as follow:

    server {
        listen 80;
        root /var/www/html/apt-front/dist;
    
        # Add index.php to the list if you are using PHP
        index index.html index.htm index.nginx-debian.html;
    
        server_name example.com www.example.com;
    
             location / {
                try_files $uri $uri/ /index.php$is_args$args;
             }
    
        location /api{
          alias "/var/www/html/api/public";
          try_files $uri $uri/ @api;
              location ~ \.php$ {
                fastcgi_split_path_info ^(.+\.php)(/.+)$;
            fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
                    fastcgi_index index.php;
                    include fastcgi_params;
                    fastcgi_param SCRIPT_FILENAME /var/www/html/mint-api/public/index.php;
        }
         }
    
           location @api {
                rewrite /api/(.*)$ /api/index.php?/$1 last;
           }
    
    
        include /etc/nginx/sites-available/*.conf;

}

I know that in AWS i would need to create a record for the domain, i believe that would be a NS record with the name of the subdomain (such as sbx.example.com). What I was thinking of doing is creating another repository (a clone) with the changes that i need for SBX, create another server block and under server name just change the subdomain? Thoughts?

I know that in AWS i would need to create a record for the domain

Yes, in any DNS you'd have to.

i believe that would be a NS record with the name of the subdomain

This would be a "A" record. This will point your Name (Domain) to your host (IP). "NS" ist for "Nameservers".

(such as sbx.example.com)

Exactly. Like this:

sbx.example.com. 1800  IN  A    127.0.0.172

Then just redirect the subdomain's request to the folders (or URIs) you need.