Assign a new specified role based on the products that are purchased in the order.

new_role_based_on_product_IDs.php

<?php

function adding_new_role_for_product_purchase() {  
  
	//add the test-1 customer role
  	add_role(
		'test-1',
    		"TEST 1 ROLE",
    		array(
      			'read'         => true,
      			'delete_posts' => false
    		)
  	);
    
  	//add the test-2 customer role
  	add_role(
    		'test-2',
    		"TEST 2 ROLE",
    		array(
      			'read'         => true,
      			'delete_posts' => false
    		)
  	);
  
}
add_action('admin_init', 'adding_new_role_for_product_purchase');



add_action( 'woocommerce_thankyou', 'update_user_role_upon_purchase_of_specified_product_IDs' );
function update_user_role_upon_purchase_of_specified_product_IDs( $order_id ) {
    
		//access the order to retrieve product's purchased
    $order = wc_get_order( $order_id );
    $items = $order->get_items();

    //define the products that should be checked for
    $products_1 = array( '920', '664' );
    $products_2 = array( '759', '663' );
    
    foreach ( $items as $item ) {
        
        //change user role based on $products_1 array
        if ( $order->user_id > 0 && in_array( $item['product_id'], $products_1 ) ) {
        	$user = new WP_User( $order->user_id );

        	// Change role
        	$user->remove_role( 'subscriber' );
            $user->remove_role( 'customer' );
        	$user->add_role( 'test-1' );

            // Exit the loop
            break;
    	}
        
        //change user role based on $products_2 array
        if ( $order->user_id > 0 && in_array( $item['product_id'], $products_2 ) ) {
        	$user = new WP_User( $order->user_id );

        	// Change role
        	$user->remove_role( 'subscriber' );
            $user->remove_role( 'customer' );
        	$user->add_role( 'test-2' );

            // Exit the loop
            break;
    	}
        
    }
}