You can't "see" truly deleted WhatsApp messages, but you can recover them via WhatsApp chat backup restore if the deletion happened after the last backup, or view them on Android phones (version 11+) using Notification History if you had it enabled, as it logs messages even after they are deleted. Third-party apps can also store notifications for deleted messages, but they are not officially supported by WhatsApp and may pose security risks.
Method 1: Restore from a Chat Backup (Android & iPhone) This method only works if you have a backup from before the message was deleted.
Method 2: Using Notification History (Android 11+)
This method allows you to see the content of a deleted message if you received a notification for it.
Method 3: Using Third-Party Apps
These apps can capture notifications and display messages that were deleted.