Hi there, @spady-ods.
The settings with your sales forms might have changed. Let me help you sort this out and email estimates with a PDF attached.
Here's how to enable this setting:
- Sign in to QuickBooks.
- Click the Gear icon and then select Account and Settings.
- Go to Sales, then click the Pencil icon on the Online delivery section.
- Check the PDF Attached box.
- Hit Save.

Once done, you can create a test estimate to check includes the PDF.
I'm also adding these articles for additional reference about emailing and printing invoices as well as customizing form styles in QuickBooks:
Please let me know how it goes or if you have additional questions. I'm here to help you anytime. Have a lovely day!