How to test
            a. Using aluminium foil as a Touch plate
Aluminium Foil
As we know aluminium is a good conductor, So you can use aluminium foil as a touch plate.
 
            b. Male to female wire or connector
Male to Female Wire or Connector
You can use the male-to-female wire/connector for touch sense, one end connected to the ESP32 GPIO pin and another end can use as a touch sense.
 
            c. Copper PCB as a touch plate
Copper PCB
We all know the PCB and it purpose, so it is also good conductor we can use as a touch plate.