The most reliable way to get a scatter file is within the for your exact device model. It's almost always included alongside other image files ( boot.img , system.img , etc.). To find the correct firmware, search online using your device's exact model number (like SM-A145R for a Samsung or CPH2591 for an OPPO) along with the term "stock firmware".
To help you find the exact firmware or solution you need, could you share the of your MTK6769 device? Share public link mt6769 scatter file hot
For advanced users: manually write to specific hot regions by sending raw commands, but this risks bricking. The most reliable way to get a scatter