1.Make sure the devices you're trying to pair are within 10 meters.
2.Go to [Settings] > [Bluetooth] and turn on [Phone Visibility].
3.During the pairing process, both Bluetooth devices will ask to confirm the pairing code. Make sure the code is correct.
4.Some devices have smart power management that may turn off Bluetooth if the battery level is too low. If your phone isn't pairing, make sure it and the device you're trying to pair with are fully charged or connected to power.
5.Restart your phone, and make sure you have the latest version of the system.
Source: Realme