How do I set the camera to save photos on the memory card (SD card)?

Solution: 

If you have inserted a memory card (SD™ card) in your realme device, the camera setting Data storage appears. Using this setting, you can select where you want to save photos and videos that you take and record.

1. From your Home screen, tap the Application screen icon.
2. Tap "System apps" > "Camera" > Enable "Save to SD card Preferred"