Where I can find the boot image??
You can find the boot image file for your Redmi 9C by following these steps:
1. Download the Platform Tools package from the official Android website.
2. Extract the contents of the downloaded zip file to a folder on your computer.
3. On your Redmi 9C, go to Settings > About phone > and tap on MIUI version seven times to enable Developer options.
4. Go to Developer options and enable USB debugging and OEM unlocking.
5. Connect your phone to your computer using a USB cable.
6. Open a command prompt or terminal window on your computer and type the command "adb devices" to confirm that your device is connected and recognized by your computer.
7. Next, type the command "adb reboot bootloader" to reboot your device into bootloader mode.
8. Once your device is in bootloader mode, type the command "fastboot devices" to confirm that your device is connected and recognized by your computer.
9. Finally, type the command "fastboot boot path/to/magisk_patched.img" to boot your device with the patched boot image file. Replace "path/to/magisk_patched.img" with the actual file path of the patched boot image file on your computer.
10. After your device has booted up, open the Magisk Manager app to start using your rooted Redmi 9C.
I hope this helps. Let me know if you have any further questions.