Final answer:
The Threat Management role provides User1 with the required permissions to view ATP reports from the Threat management dashboard.
Step-by-step explanation:
The role that provides User1 with the required permissions to view Advanced Threat Protection (ATP) reports from the Threat management dashboard in a Microsoft 365 subscription is Threat Management.
The Threat Management role is specifically designed to manage security features such as ATP, and it includes permissions to view ATP reports and perform other related tasks.
The other roles mentioned, Security Administrator, Security Operator, and Compliance Administrator, may have some administrative access in Microsoft 365, but they do not have the specific permissions to view ATP reports from the Threat management dashboard.