Hello, @NBO.

The feature to create a sales order in QuickBooks Online (QBO) is still unavailable. However, you can create an estimate and then turn it into an invoice at a later time. 

You'll create an estimate and send it to your customer for a quote, bid, or proposal for work you plan to do. Then, convert it into an invoice when the customer accepts the estimate. 

Also, you can copy an estimate into a purchase order if you'll be sending it to a vendor. Check this article for more information: Copy an estimate to a purchase order.

If you have other follow-up concerns about this, let me know. I'm always here to assist. Take care and have a wonderful day!