In order to use Bluetooth functions, the Samsung device and another device must first be paired. The process can differ depending on the device. For smartphones, both devices only need to agree to the pairing. Car radios usually require a code to be entered on the Samsung device. For Bluetooth headsets, it is sufficient to simply pair the devices, without the need for a code or similar.

Once the Samsung device is connected to another, this device is stored and does not require a code for further connections.

Android 10 (One UI 2.0)
Step 1:  Open the  Settings
Step 2:  Tap on  Connections
Step 3:  Tap on  Bluetooth
Step 4:  Tap on desired  device
Step 5:  Confirm with  OK
  1. Open the Settings
  2. Tap on Connections
  3. Tap on Bluetooth
  4. Tap on desired device
  5. Confirm with OK

Samsung Instructions