Hi Jkelly21,
I can see how helpful to have access that lets employees create an invoice without turning on the sales and other options.
As of now, this feature is unavailable in QuickBooks. I'd suggest sending Feedback to our developers. You can share this suggestion by clicking the Gear icon, then selecting Feedback.
You can track feature requests through the QuickBooks Online Feature Requests website.
I've also added these references as your employee's guide in creating invoices:
I'm just a post-away if there's anything that I can help with sending transactions.