In simple terms, firmware is the low-level software embedded in your phone’s hardware. While your "OS" (Android 11/12) is what you interact with daily, the firmware is the operating system for the hardware components—the touchscreen, battery controller, camera sensors, and radio antennas.
: According to recent community reports, the Reno 5 series has largely reached its end-of-life for major OS updates and is not expected to receive Android 15. OPPO Global Community How to Check or Install Updates Over-the-Air (OTA) Settings > About Device > Software Update firmware oppo reno 5f