When you buy a UiCore theme, you'll get free access to the Figma design file.
To access the file, log in to your https://my.uicore.co/ account and click on "Request Figma Access":
You will receive an email with the Figma File link. To edit the file, simply click on "Duplicate to Your Drafts" to create a copy of the file in your account. This will allow you to make changes without affecting the original file:
Please note that the Figma file is not available for the following themes: Affirm, Landio and Brisk.