How to output data of SERVO_32 channel through serial port

After I turn on SERVO_32ENABLE, the output of the servo will have 32 channels, but there are not as many interfaces on the board. Therefore, I consider using a serial port to output signals (sbus or crsf), and then using a conversion board to output PWM signals of 16-32. However, there are no 16 to 32 SBUS outputs in the serial port options. So, how should I output signals from 16 to 32?