If you decide to try an installer anyway, look for — that was the most stable version for MIUI 12.5 Android 10. Always back up your data first.
It sounds like you're looking for a way to install Google services (Play Store, Gmail, etc.) on a Xiaomi device running — likely a phone that came without Google services (e.g., a China-ROM device). Google Installer For Miui 12.5.5 Android 10 - Google