Survey URL

Hello
I have been researching "embedded data" feature to try and accomplish something however I have not been successful in understanding how to set it up.
What I am trying to do is have a base/core survey URL and then manually add a unique variable at the end to make it unique that I can provide to a user. This way I can just manually add the variable such as the customer name and then send it to the customer to complete.
Example - Base URL https://survey.qualtrics.com/fe/form/SID=SV_1234
Example - Finale URL that is provided to user https://survey.qualtrics.com/fe/form/SID=SV_1234XXXXXXXXX