I used a 27 resistance since i used the ohm law: 1,3/0.05 = 27?
Did i get something wrong?
Yes this is not the way to do anything. You can not use resistors to reduce the voltage.
You need to get a 3V voltage that is capable of powering your device. How much current does your device take?
Then you need to switch that with a transistor.
Arduino output -- 2K7 --- transistor base
Transistor emitter to ground
device ground to transistor collector
device power to your 3V supply +ve
3V supply ground to arduino ground.