You can save a Draft of an envelope to complete later. What you may be alluding to is the creation or usage of a Template that has set structure for the Recipients and the Email Subject and Email Body of those Recipients, which when applied to an envelope could be modified prior to Sending the envelope. I use Templates in a variety of ways and one of those methods is an Overlay. So I setup two Templates with the same blank document, then set different Recipient structures and emails to accommodate for different needs when the envelope is created. One circumstance might apply 3 Recipients each with unique emails, and another applies 3 Recipients but with one generic email for all 3. So I would suggest using or exploring Templates as the answer to your question. Here is a DocuSign article as a good starting point but feel free to ask follow-up questions...

https://support.docusign.com/en/guides/ndse-user-guide-create-templates

​​So what you are saying is that I can save a few different Templates that can be used as the message of the email that I send when sending an envelope. It would just be called an Overlay?

Somewhat correct. There would be one or more Templates and each Template would be unique in the Recipient structure or just the email associated to those Recipients. So you could have two Templates, lets call them Template A and Template B, both have 3 Recipients, but Template A has email subject and body that are different from Template B.

When I look at Template there are several ways to view them, I look at them as "Fillable" and "Overlay" (my terms) and of course combinations of these. Basically a "fillable" template is one that you add all DocuSign fields to and typically you complete the form in DocuSign and send it for Signatures. Overlay is used more often when the document is completed prior to uploading to an envelope. Typically "use" a template is the fillable where "apply" is the overlay, but as noted I could "use" a Template and "apply" another or several to add layers.