Command code manual:

Motor control command format

m[DIR][MOTOR][PWM]
DIR -> f - forward, b - backward, r - right, l - left, s - stop, c - custom
Motor -> 0 or 1
PWM -> (0-255)

Servo control command format

s[servo_number][pos]
pos -> (0-180)

Custom control command format

st
[motor/servo command]
[motor/servo command]
.
.
.
end

https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json link for arduino ide esp32 board installation