How can I create custom endpoint with post and get methods on wordpress api

I'm trying to make a custom endpoint, for example: https://localhostname.com/wp-json/company_name/settings

Where I'll keep some settings like theme colors and other things, but it seems there are many ways to do that and I just want the simplest way. All the searching on the web is making me really confused. So basically I want to make a POST request to the above URL like this:

{
  "primary_color": "0xFFFFFFFF",
  "secondary_color": "0xFFFFFF11"
}

and then get these same parameters in a GET request.

It's just that. No verification at all. Sorry if it's that simple, but I'm really having a hard time with this problem as I am not used to program with php at all.

To create a custom endpoint you will need to add below snippet to your function file:

add_action( 'init', 'setup_init' );


function setup_init() {

   add_action( 'rest_api_init', 'custom_endpoint' );

   function custom_endpoint() {

    register_rest_route( 'company_name', '/settings', array(
        'methods' => 'GET',
        'callback' => 'custom_callback',
    ));
}

   function custom_callback($request_data){
       return 'hello world';
   }
}

Let me know if any query and do accept the answer if it works :)