When I registered my complaint with the customer care in Samsung Members, the only advice they gave me was to switch off all functions like BT, WiFi, Mobile Data, Sync, Screen Rotation, use adaptive brightness, switch off location and practically everything. Then what is the point in using a smart phone that costs thousands of rupees? Better to use a feature phone for Rs.1000.
The phone is draining even in Safe Mode which confirms it is a OS problem. But you are not ready to accept it. And my problems started only after updating to Android 10.