Hi jtout0431,
Being able to send invoice reminders using QuickBooks Online application is a great feature.
Currently, sending overdue reminder templates on the QuickBooks app is unavailable. It is only available when accessing QBO through a web browser. While this option is unavailable, I'd recommend sending feedback to our developer's team. You can do that by clicking the Gear icon and then selecting Feedback.
You can track feature requests through the QuickBooks Online Feature Requests website.
If you want to include PDF copies of the invoices, you can check this reference: Send invoice reminders automatically or manually.
Please let me know if you have other questions related to QuickBooks. I'm always here to help you.