Hello @LeslieCohenDesign,
Welcome to the Community space. I can share information to your question about the invoices in QuickBooks Online.
Your customer will still have the Pay Invoice button within the email. The basis would be the option selected within the invoice in QuickBooks.
If you enable online payments, the button will be available from your customer's end. However, the amount will turn to zero if you void the transaction after sending it to someone.
In QuickBooks Desktop, you can also email sales forms by batch. For more information about the steps, check out this article: Email sales forms, invoices, and statements in QuickBooks Desktop.
Keep us posted if you need anything else about your sales transactions in QuickBooks. I'll be here to help. Have a great day.