How can I rotate a character 180 degrees by D, and -180 by A

I try to move a 3d character like a 2d character in a platform game.
What I mean is; when I press D, the character rotate and move to the right ,
and when I press A, the character rotate and move to the left .
I was thinking to reference the local axis of the character to the world axis && press A,D than rotate 180 degrees, else - stay your current direction .
I dont know if its the way to do it, and I dont know how to code it.
Im new to c#/
Thank you

just wrote a quick demo for you. Basically it takes two keyboard input:

  1. when user press A and B it uses transform.Rotate method, while passes a vector as it’s rotation direction and speed.

    using UnityEngine;
    using System.Collections;

    public class rotate : MonoBehaviour {

     // Update is called once per frame
     void Update () {
         if (Input.GetKey(KeyCode.A))
         {
             rotateMove(-1);
         }
         else if (Input.GetKey(KeyCode.D))
         {
             rotateMove(1);
         }
     }
    
     private void rotateMove(int dir)
     {
         gameObject.transform.Rotate(0, dir, 0);
     }
    

    }

Thanks a lot, realy appreciate your answer,
I come from the world of 3d, not scripting,
if you need anything - help with modeling ,texturing…whatever I can help, just ask.