Sensitivity labels can be applied to modern Office file types that support protection:
Supported: .docx, .xlsx, .pptx, etc.
Not supported: Legacy formats like .doc or non-Office formats like .txt.
Therefore, only File2.docx and File3.xlsx can have Label1 applied.
Reference: File types supported for sensitivity labels

Explanation:

To validate whether an audit log retention policy will apply to the intended entries, you should configure the following fields:
# Date and time range (UTC) ensures that you are searching for audit logs within the time period when the policy should be applied. Audit logs are time-sensitive, and policies affect logs based on their timestamp.
# Record types allows you to filter and search for specific audit log categories (e.g., Exchange, SharePoint, Teams, etc.) that are affected by the retention policy. Selecting the correct record type ensures that the policy is evaluated against the relevant data.

Adding a folder path to the file path exclusions in Microsoft 365 Endpoint DLP does not prevent Tailspin_scanner.exe from accessing protected sensitive information. Instead, it would exclude those files from DLP protection, which is not the intended outcome.
To block Tailspin_scanner.exe from accessing sensitive documents while allowing it to access other files, the correct solution is to use Microsoft Purview Endpoint Data Loss Prevention (Endpoint DLP) and add Tailspin_scanner.exe to the Restricted Apps list.
Endpoint DLP allows you to block specific applications from accessing sensitive files while keeping general access available. Restricted Apps List in Endpoint DLP ensures that Tailspin_scanner.exe cannot open, copy, or process protected documents, but it can still function normally for non-sensitive content.

Step 1 - Understanding the requirement
You want to retain specific audit log record types and activities for 3 years:
CopilotInteraction # All activities (1/1)
Compliance DLP endpoint # All activities (2/2)
Azure Active Directory # Only 2 out of 25 activities selected (Reset user password, Changed user password) The goal is to minimize the number of audit retention policies while meeting the requirement to store only the selected record types and activities.
Step 2 - Audit retention policies in Microsoft Purview
Audit retention policies let you define which activities and record types are retained and for how long.
A single retention policy can include multiple record types and multiple activities.
Limitation: Each policy can only define one set of retention settings per included record types/activities.
If you want to retain different subsets of activities (e.g., only 2 out of 25 in Azure AD), you must create a separate policy for that.
# Reference: Set up audit (Premium) retention policies in Microsoft Purview Step 3 - Applying to the scenario CopilotInteraction: Since you need all activities, you can include them in one policy.
Compliance DLP endpoint: Since you also need all activities, they can be added to the same policy as CopilotInteraction.
# These two can be covered by 1 policy.
Azure Active Directory: You only need 2 out of 25 activities. Since this requires activity-level filtering, it must be placed in a separate policy.
Thus:
Policy 1 # CopilotInteraction (all) + Compliance DLP endpoint (all)
Policy 2 # Azure AD "Reset user password"
Policy 3 # Azure AD "Changed user password"
That equals 3 total policies.

The requirement is that User1 must be able to analyze prompts and responses for AI interaction events in Microsoft Purview DSPM for AI, while following the principle of least privilege.
Information Protection Analysts role group:
Members can review and analyze sensitive data activity, including AI interaction events collected by Purview DSPM. This role is specifically intended for analysts monitoring sensitive information and is therefore necessary for User1.
Content Explorer List Viewer role group:
Members can see metadata about items with sensitive information, such as file names, locations, sensitivity labels, and policy matches, without accessing the actual file content. This provides the required visibility for AI-related data classification and interaction analysis while adhering to the least privilege principle.
Roles not required:
Content Explorer Content Viewer would give the ability to view the actual content of files, which is more access than needed.
Security Reader is intended for reviewing alerts and incidents but not for analyzing AI prompts and responses.
Insider Risk Management Investigators focus on insider risk investigations, not AI event analysis.
References:
Microsoft Learn: Microsoft Purview compliance portal permissions
Microsoft Learn: Use Content Explorer in data classification