Method 1:
realme UI 3.0 & above versions: Long press the app icon > App info > Manage notifications > Turn off Vibrate
realme UI 2.0 & 1.0: Not supported
realme UI R & Go & T & S & U Edition: Not supported
Method 2:
realme UI 3.0 & above versions: Settings > Sound & vibration > Vibration intensity > Turn off the Notification vibration
realme UI 2.0: Settings > Sound & vibration > Reduce notification feedback on full screen
realme UI T & U Edition: Settings > Sound & vibration > Vibration & haptics > Notification vibration
realme UI 1.0: Not supported
realme UI R & Go & S Edition: Not supported

Related Articles:
How to disable the notification sound
How to set silent notifications