Hi, my intent was to create a 3-axis stabilizer with 3 stepper motors (driven by an A4988 driver), but I have no idea how to vary the angle of the motors according to the variation of the data provided by the MPU6050. Can anyone help me or give me a code? thank you very much!

Do a search for PID and learn how PID works. You would have a setpoint, an input and an output variables. The setpoint could be 0 degrees. The input would be the measured angle. Then you calculate the error (input - setpoint). The output is then the error times some coefficient. The sign of the error tells you the direction to move the motor. The amplitude of the error can set the speed of the motor response.

Ok i will do some research. Thank you very much