Hi darcy-mykytyshyn,
Welcome to Community! I can see the benefit of having a surcharge automatically applied to your invoices in QuickBooks Online. However, this feature isn't available at this time. If you would like to see this in future updates, please don't hesitate to submit a suggestion to our Development Team. In the interim, you can manually add service fees by following the steps here.
If you have any other questions, please don't hesitate to reach back out. We'd be happy to help!