The vibration function is not working

@volkankarasay first check what Realme suggest:

Check Sound and Vibration Settings

• Go to Settings > Sound & vibration.
• Make sure Vibration on ring or Vibrate for calls is turned on.
• Turn on Vibration Sync with ringtone (note that this requires using a default system ringtone).
• Tap Haptics & tones and enable System haptics for touch feedback.

Next check this:

• Check your Control Center or go to Settings > Do Not Disturb to verify it is turned off, as DND silences all vibrations and alerts.
• Make sure Battery Saver is disabled, as power-saving modes often restrict haptic feedback.

Finally run the hardware diagnostics test:

• Open the Phone Manager app, tap Tools (or the grid icon), select Diagnostics, and run a dedicated Vibration test.
• Alternatively, open the phone dialer and enter *#899# or *#89# to access Engineer Mode, navigate to Manual Test > Device Debugging, and run the vibration test.

If the failure is not related to any of your settings, you may have a failed vibrator motor and will need to replace it. Since iFixit does not yet have a specific guide for this, use something like this video at the end of the video you see the vibrator on the bottom right side. You do not have to remove the screen or even to main board. You should get to the vibrator by removing the speaker and the charging board.