Wordpress plugin code to register a custom route

custom-api-route-2.php

add_action('rest_api_init', 'register_custom_route');

function register_custom_route() {
    register_rest_route('custom-api-route/v1', '/submit', array(
        'methods' => 'POST',
        'callback' => 'process_data_submission',
        'permission_callback' => '__return_true',
    ));
}