Yes, Jeremy. The functionality to import invoices is always available, except in the QuickBooks Online (QBO) Simple Start version. Allow me to provide the steps and additional information about it.
Here's how to import invoices:
Go to the Gear icon and select Import Data.
Select Invoices and click Import.
Browse and select the spreadsheet of your invoices.
Additionally, if you encounter a notice stating, "Import invoices aren't quite ready to support sales tax. We're working on it. Support for sales tax will be coming soon," it means that the Sales Tax feature is enabled.
If you don't collect sales tax on products and services in QuickBooks, consider turning off the feature. However, you'll need to delete all sales tax transactions first. For a step-by-step guide, check out the article: Turn off sales tax in QuickBooks Online.
Moreover, I've attached these articles for future reference in managing invoices and payments in QuickBooks:
If you need further clarification on importing invoices or other data in QuickBooks, please feel free to respond in this thread. I'm always available to assist you.