Youtube Zoom Example

using UnityEngine;

public class OppositeAnimZoom:MonoBehaviour
{
    public Transform cameraTransform;
    public float duration = 10;
    public AnimationCurve zoomCurve = AnimationCurve.Linear(0, 0, 1, 1);
    public AnimationCurve rotationCurve = AnimationCurve.Linear(0, 0, 1, 1);
    public int targetZoom = 3;

    private bool started;
    private int startZoom;
    private float time = 0;
    private Vector3 originalScale;
    private Transform mapTransform;
    private OnlineMaps map;
    private Vector3 originalPosition;
    private Vector3 smoothZoomOffset;

    private void OnGUI()
    {
        if (!started && GUILayout.Button("Start"))
        {
            startZoom = OnlineMaps.instance.zoom;
            started = true;
        }
    }

    private void Start()
    {
        map = OnlineMaps.instance;
        mapTransform = map.transform;
        originalPosition = mapTransform.localPosition;
        originalScale = mapTransform.localScale;

        Vector3 smoothZoomHitPoint = originalPosition + mapTransform.rotation * new Vector3(map.tilesetSize.x / -2 * originalScale.x, 0, map.tilesetSize.y / 2 * originalScale.z);
        smoothZoomOffset = Quaternion.Inverse(mapTransform.rotation) * (originalPosition - smoothZoomHitPoint);
        smoothZoomOffset.Scale(new Vector3(-1f / map.tilesetWidth, 0, -1f / map.tilesetHeight));
    }

    private void Update()
    {
        if (!started) return;

        time += Time.deltaTime / duration;
        if (time >= 1)
        {
            started = false;
        }

        float _zoom = startZoom - zoomCurve.Evaluate(time) * (startZoom - targetZoom);
        Vector3 camAngles = cameraTransform.localRotation.eulerAngles;
        camAngles.y = 180 - rotationCurve.Evaluate(time) * 360;
        cameraTransform.localRotation = Quaternion.Euler(camAngles);

        float offset = _zoom - (int)_zoom + 1;
        Vector3 newScale = originalScale * offset;

        mapTransform.localScale = newScale;
        Vector3 s = newScale - originalScale;
        s.Scale(new Vector3(1f / originalScale.x, 1 / originalScale.y, 1 / originalScale.z));
        Vector3 p = mapTransform.rotation * new Vector3(map.tilesetWidth * s.x * smoothZoomOffset.x, 0, map.tilesetHeight * s.z * smoothZoomOffset.z);
        mapTransform.localPosition = originalPosition - p;
        map.zoom = (int) _zoom;
    }
}