Update item custom quantity and salable quantity value after place order in Magento 2

Question

I need to decrease purchased item saleable quantity with custom value (x* ordered_qty) after place order in Magento 2.Right now I'm using the following observer and class to update the quantity of purchased items.

Event Xml

    <event name="sales_order_place_after">
       <observer name="Update_customstock" instance="Company\MyMoudle\Observer\UpdateStock" />
   </event>

Observer Class

class UpdateStock implements ObserverInterface
{


    public function execute(\Magento\Framework\Event\Observer $observer)
    {

     $orderData = $observer->getEvent()->getOrder();
     $orderItems = $orderData->getAllVisibleItems();
               foreach($orderItems as $item) {
                      if($flag_variable) {
                $stockItem->setIsInStock(true);
                $stockItem->setQty($new_qty);
               $this->stockRegistry->updateStockItemBySku($item->getSku(), $stockItem);
                     }
        }
    }

}

Issue

But it's deceasing salable quantity double of my sent value and quantity also updating as sent value.

What I need

I need if the order is placed then only the decrease the salable quantity and once the shipment is created then decrease the quantity.

Please suggest any solution with a plugin or observer.

Answer 1

Use the following event global scope. Ex. VendorName/ModuleName/etc/events.xml

checkout_submit_all_after

For Paypal payment method, use the following:

paypal_express_place_order_success

Answer 2

Just go to Catalog -> inventory on the store configuration in the back end.

In the stock options, select No to Decrease Stock When Order is Placed. Then you will get what you needed.