Zoom in/zoom out on mouse left and right click in Unity (works only in perspective mode)

 This is a very simple code. Just create a new C# script named as CameraInOut, place this code in it, and add it to the main camera. It will start zooming in on the left click and zooming out on right-click.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
 
public class CameraInOut : MonoBehaviour
{
    public float[] FOVS = {45, 30, 15};
    public float speed = 2f;
    public bool zoomIn, zoomOut;
    Camera myCamera;
    int FOVpos = 0;
 
    void Start()
    {
        myCamera = GetComponent<Camera>();
    }
 
    void Update()
    {
        if(Input.GetMouseButtonDown(0))
        {
            ZoomIn();
        }
 
        if (Input.GetMouseButtonDown(1))
        {
            ZoomOut();
        }
 
        if(zoomIn)
        {
            myCamera.fieldOfView = Mathf.Lerp(myCamera.fieldOfView, FOVS[FOVpos], speed * Time.deltaTime);
            if(Mathf.Approximately(myCamera.fieldOfView, FOVS[FOVpos]))
            {
                zoomIn = false;
            }
        }
 
        if (zoomOut)
        {
            myCamera.fieldOfView = Mathf.Lerp(myCamera.fieldOfView, FOVS[FOVpos], speed * Time.deltaTime);
            if (Mathf.Approximately(myCamera.fieldOfView, FOVS[FOVpos]))
            {
                zoomOut = false;
            }
        }
    }
 
    void ZoomIn()
    {
        if (FOVpos >= FOVS.Length - 1)
        {
            FOVpos = FOVS.Length - 1;
        }
        else
        {
            FOVpos += 1;
        }
 
        zoomIn = true;
    }
 
    void ZoomOut()
    {
        if (FOVpos <= 0)
        {
            FOVpos = 0;
        }
        else
        {
            FOVpos -= 1;
        }
 
        zoomOut = true;
    }
}