Apple Watch Series 10
It's not possible to connect to another Bluetooth device
Solution 1 of 6: Bluetooth is turned off on your Apple Watch
Bluetooth is a wireless connection which can be used to connect to, e.g., a wireless headset.
Press the Digital Crown.
Press the settings icon.
Press Bluetooth.
Press the indicator next to "Bluetooth" to turn the function on or off.
Press the Digital Crown several times to return to standby mode.