Let me be the first to welcome you to the Community. I'm here to walk you through the steps to print a packing slip in QuickBooks Online.
If you've already created an invoice or a sales receipt, you should be able to print a packing slip. Here's how:
Go to Sales from the left menu and select Customers.
Click the customer's name to display a list of their transactions.
From the Transaction List tab, select an invoice or a sales receipt for which you want to print a packing slip.
Select the Batch actions drop-down, then choose Print packing slip.
Here's an article for your reference: How to create a packing slip in QuickBooks Online.
With these steps, you should be able to create and print a packing slip.
That should do it. Let me know what else I can do to help you succeed today. If you have questions, leave a reply below. I'll be more than happy to answer them for you. Have a wonderful day and take care!