Senzing currently ships with a synthetic truth set that can be accessed vie the Senzing App or the API.
See the App Quickstart Guide for getting started with the desktop application. It already has a synthetic truth set loaded in the demo project.
See the Exploratory Data Analysis 1 - Loading the truth set demo for getting started with the APIs. The truth sets it uses are also shipped with the product.
Finally, see the How to create an entity resolution truth set if you are interested in building your own truth set.