With QBO can I use the subtotal function like in Desktop?

I'm here to help you enable the subtotal option in QuickBooks Online (QBO), @ESII.

Adding a subtotal option is possible in QBO. If you want to add it to the invoice or estimate, select a Product & services, then click the Add product &services dropdown to add a subtotal. Please refer to the screenshots below. 

Whenever you need to personalize any sales forms, refer to this article for further help: Customize invoices, estimates, and sales receipts.

Don't hesitate to reach us if you have other questions about functions in QBO. Take care.

Yes, it worked, thank you so much for your help.

Hello, ESII.

I'm very glad that the information was able to help you. It warms our hearts when we receive positive messages from our valued customers.

The Community will always be around to lend you a hand any time you need guidance. If you have any other questions or concerns, don't hesitate to ask. Enjoy your day!