Stepper motor control
No, that will not do what you want. That will continuously rotate the stepper round and round and round.

The clue as to why is in the name of the function you put the myStepper.step call: "loop". That function repeatedly loops around over and over again, so your step function will be called over and over again.

There is one piece of information lacking from your thinking at the moment, and that is when do you want the stepper to rotate? If it's just once when you turn the power on then it's as simple as doing everything (including calling myStepper.step) in setup() and leaving loop() empty. If not, then you will need to add appropriate logic to only run the step function when the required conditions are met.