Oppo F3 Plus Nougat Update Forum Xda -

Because this update is no longer pushed Over-The-Air (OTA), you must flash it manually using the stock recovery.

While a Nougat-based firmware ( ColorOS 3.1 ) was eventually made available for the Go to product viewer dialog for this item. oppo f3 plus nougat update forum xda

Turn off your device. Press and hold the Power and Volume Down buttons simultaneously until the Oppo logo appears. Because this update is no longer pushed Over-The-Air