In order to connect the Samsung device to other devices via Bluetooth, Bluetooth itself must first be activated. Stored Bluetooth connections are automatically established when they are in the vicinity, such as cars or even loudspeakers. If Bluetooth is not used, the function should be switched off in order to avoid unnecessary strain on the battery.

Note: Bluetooth can also be switched on/off via the quick settings.

Android 10 (One UI 2.0)
Step 1:  Open the  Settings
Step 2:  Tap on  Connections
Step 3:  Enable or disable  Bluetooth
  1. Open the Settings
  2. Tap on Connections
  3. Enable or disable Bluetooth

Samsung Instructions