If you are looking to "download firmware" for your Android device, you are likely looking for one of the following:
Use tools like Frija or websites like SamMobile and SamFw (requires specific model numbers like SM-G991B). Xiaomi/Poco: Xiaomi Firmware Updater OnePlus: Official OnePlus Support Page How to Install (Flash) Firmware skachat proshivku iso na android
Uses the Android Flash Tool (web-based) or fastboot commands via terminal. If you are looking to "download firmware" for