Explanation:

Step 1 - Review scenario
You created a retention label policy Contoso_Policy.
Status shows Off (Error) with message: "It's taking longer than expected to deploy the policy." Requirement: Reinitiate the policy.
Step 2 - Correct PowerShell cmdlet
To manage retention label policies in Microsoft Purview (compliance), the cmdlet is:
Set-RetentionCompliancePolicy
Other cmdlets:
Set-RetentionPolicy # Legacy Exchange Online retention policies, not Purview label policies.
Start-EdgeSynchronization # Sync for Edge Transport servers, not retention.
Start-RetentionAutoTagLearning # Used for auto-tagging learning, not relevant here.
Step 3 - Correct parameter
To force redistribution of a retention label policy when deployment fails, the parameter is:
-RetryDistribution
Other options:
-ForceFullSync and -FullCrawl # Apply to search/crawl, not retention.
-Train # Related to auto-tagging learning models, not retention.
Final Verified Answer
Set-RetentionCompliancePolicy -id Contoso_Policy -RetryDistribution
Reference:
Set-RetentionCompliancePolicy (Microsoft Purview PowerShell)