RoApp/Assets/CinemachinePostProcessingV2/Samples~/Cinemachine Example Scenes/Scenes/BossCamera/CustomLockCameraY.cs

using UnityEngine;

namespace Cinemachine.Examples
{
    /// <summary>
    /// An add-on module for Cinemachine Virtual Camera that locks the camera's Y co-ordinate
    /// </summary>
    [ExecuteAlways]
    [SaveDuringPlay]
    [AddComponentMenu("")] // Hide in menu
    public class CustomLockCameraY : CinemachineExtension
    {
        [Tooltip("Lock the camera's Y position to this value")]
        public float m_YPosition = 10;

        protected override void PostPipelineStageCallback(
            CinemachineVirtualCameraBase vcam,
            CinemachineCore.Stage stage, ref CameraState state, float deltaTime)
        {
            if (stage == CinemachineCore.Stage.Finalize)
            {
                var pos = state.RawPosition;
                pos.y = m_YPosition;
                state.RawPosition = pos;
            }
        }
    }
}