SwitchVirtualCameraArea.cs

using Cinemachine;
using UnityEngine;

[RequireComponent(typeof(Collider2D))]
public class SwitchVirtualCameraArea : MonoBehaviour
{
    [SerializeField] private CinemachineVirtualCamera targetVirtualCamera = default;
    private CinemachineVirtualCamera TargetVirtualCamera => targetVirtualCamera;

    private CinemachineBrain cinemachineBrain;

    private const int EnableVirtualCameraPriority = int.MaxValue;

    private void Start()
    {
        this.cinemachineBrain = Camera.main.GetComponent<CinemachineBrain>();
        this.GetComponent<Collider2D>().isTrigger = true;
    }

    private void OnTriggerEnter2D(Collider2D collider)
    {
        if (!collider.CompareTag("Player"))
        {
            return;
        }

        this.DisableCurrentVirtualCamera();
        this.EnableTargetVirtualCamera();
    }

    private void DisableCurrentVirtualCamera()
    {
        var current = this.cinemachineBrain.ActiveVirtualCamera as CinemachineVirtualCamera;
        current.Priority = 0;
    }

    private void EnableTargetVirtualCamera()
    {
        this.TargetVirtualCamera.enabled = true;
        this.TargetVirtualCamera.Priority = EnableVirtualCameraPriority;
    }
}