Opening Fastboot Mode on an OPPO A74 is intentionally difficult because OPPO does not want casual users tampering with the firmware. While the is the most reliable for entering a low-level state, actually getting to the Fastboot menu often requires an authorized unlock from OPPO.
If your device is powered on and you have a computer, you can use ADB commands Enable Debugging Settings > About Phone Build Number seven times to enable Developer Options. Then, go to Developer Options and enable USB Debugging Connect to PC : Connect your OPPO A74 to your computer via a USB cable. Run Command : Open a Command Prompt or Terminal on your PC and type: adb reboot bootloader how+to+open+fastboot+mode+on+oppo+a74+best