QuickBooks Online (QBO) doesn't offer a direct option to link an estimate to a sales order, coact.

In QBO, estimates and sales orders function differently within the program's workflow. Estimates are non-posting transactions meant to be converted directly into invoices and serve as proposals for customers.

In contrast, sales orders are used to track inventory and manage orders before any invoices are created.

If you want to connect these two types of transactions, you may consider exploring third-party applications designed to bridge the gap between estimates and sales orders in QBO.

Feel free to reply to this post if you need further assistance.