SceneCreator.cs

using System;
using System.IO;
using UnityEditor;

public static class SceneCreator
{
    [MenuItem( "Assets/Create/Empty Scene" )]
    private static void CreateEmptyScene()
    {
        CreateScene( 
            "New Empty Sene", 
            EditorApplication.NewEmptyScene 
        );
    }
    
    [MenuItem( "Assets/Create/Scene" )]
    private static void CreateScene()
    {
        CreateScene( 
            "New Sene", 
            EditorApplication.NewScene 
        );
    }

    private static void CreateScene( 
        string filenameWithoutExtension, 
        Action newSceneCallback 
    )
    {
        var filename = filenameWithoutExtension + ".unity";
        var path = GetPath() + "/" + filename;
        path = AssetDatabase.GenerateUniqueAssetPath( path );

        newSceneCallback();
        
        EditorApplication.SaveScene( path );

        var scenes = EditorBuildSettings.scenes;
        ArrayUtility.Add( 
            ref scenes, 
            new EditorBuildSettingsScene( path, true )
        );
        EditorBuildSettings.scenes = scenes;
    }

    private static string GetPath()
    {
        var instanceId = Selection.activeInstanceID;
        var path = AssetDatabase.GetAssetPath( instanceId );
        path = string.IsNullOrEmpty( path ) ? "Assets" : path;

        if ( Directory.Exists( path ) )
        {
            return path;
        }
        if ( File.Exists( path ) )
        {
            var parent = Directory.GetParent( path );
            var fullName = parent.FullName;
            var unixFileName = fullName.Replace( "\\", "/" );
            return FileUtil.GetProjectRelativePath( unixFileName );
        }
        return string.Empty;
    }
}