Beepers tab
If required the Beeper function can be enabled on UART pin, the example below can be copied and pasted into the CLI section then type save and enter. This example has the Beeper on UART(B) RX pin
resource SERIAL_RX 6 NONE
resource BEEPER 1 C06
The Beeper required MUST be a 5v active low and buffered to protect the UART output.
These have been tested and working, you may find these or similar local to your location.
Under the Beepers tab in the Rotorflight configurator you can select the required alerts