Hello,
I'm quite new to script writing, so I would strugle with harder codes than controlling servos, LEDs etc.
I want to make a code that would be activated by certain strength of RC car receiver throttle signal(the code would activate at certain amount of RPMs and stop if lower). But I don't know how to write it. 
Please help with that.
In loop():
if (rpm > thresholdValue) {
// do stuff for high rpm
}
where rpm is the latest rpm reading,
Is this usable with rc car receivers like this: https://hobbyking.com/en_us/hobbykingr-tm-gt-2-2-4ghz-receiver-3ch.html
Can you read that signal with an Arduino and does it provide an rpm value?
If so: yes.
You have two clear options.
Either monitor the PWM signal on the servo to give you a throttle position.
https://www.electronoobs.com/eng_robotica_tut9_1.php
Or put a small sensor on the output of the motor to give actual RPM.