Welcome aboard to the Community, Leah.
To embed a QRcode into your invoices, you'll have to use a third-party application. This is because the mentioned feature is currently unavailable in QBO.
I recommend visiting the Intuit Marketplace to find one. The portal is a one-stop-shop where you'll find apps that integrate with QuickBooks.
You can also check the customers' reviews to help decide which one suits your needs most. Simply click the Learn more link to see the complete information.
Let me know if you have any other concerns or questions. Please know I’m here ready to assist further. Have a good one.