Hi Heather,
When you reply an email in Outlook client but don’t send it, it will show as a Draft email. You can directly double click the previous email to open the previous email and view the attachments in the previous email. Here is an example for Outlook for Windows client.
If you have any further concern about this behavior, please vote for this feature via this link: https://outlook.uservoice.com/forums/322590-outlook-2016-for-windows/suggestions/13835472-returning-to-the-original-message-when-typing-a-dr
Thanks for your understanding.
Barry