ServiceNow by default provides two environments. One for production and another for a non-prod.
Depending on your testing architecture you can purchase additional environments depending on your purpose.
Additionally, to provide further insights on how the different types of testing is implemented in ServiceNow instances, you can find two links that will assist you and more information both for performance and VAPT.
Performance Testing
Vulnerability and Penetration Testing (VAPT)
Thanks,
Bill
