·> Так надо телегу за лошадью ставить, тогда всё просто:

·>var dic = new Dictionary<(int code,string value, List<MyCodeValueContainerBlaBlaBla>)>();
·>

class AAA
{
    private Dictionary<(int code,string value, List<MyCodeValueContainerBlaBlaBla>)> _dic = new();
}

IT>class AAA
IT>{
IT>    private Dictionary<(int code,string value, List<MyCodeValueContainerBlaBlaBla>)> _dic = new();
IT>}
IT>

private Dictionary<(int code,string value, List<MyCodeValueContainerBlaBlaBla>)> _dic = new Dictionary<>();

private Map<...very many type params> _dic = new ConcurrentHashMap<>();

ReadOnlySpan<byte> span = stackalloc byte[10]
{
    1, 2, 3, 4, 5, 6, 7, 8, 9, 10
};

var x = new MyList { a, b, c };

var tmp = new MyList();
tmp.Add(a);
tmp.Add(b);
tmp.Add(c);
var x = tmp;

property[MyStyle1] string? Location
{
    //...before
    _location = value;
    //...after
}

private string? _location;
public  string?  Location
{
    get { return _location; }
    set
    {
        if (_location != value)
        {
            //...before
            _location = value;
            //...after
        }
    }
}

S_S>property[MyStyle1] string? Location
S_S>{
S_S>    //...before
S_S>    _location = value;
S_S>    //...after
S_S>}
S_S>

using PropertyChanged.SourceGenerator;
public partial class MyViewModel
{
    [Notify] private string _lastName;
    public string FullName => $"Dr. {LastName}";
}

partial class MyViewModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    public string LastName
    {
        get => _lastName;
        set
        {
            if (!EqualityComparer<string>.Default.Equals(_lastName, value))
            {
                _lastName = value;
                OnPropertyChanged(EventArgsCache.LastName);
                OnPropertyChanged(EventArgsCache.FullName);
            }
        }
    }

    protected virtual void OnPropertyChanged(PropertyChangedEventArgs args)
    {
        PropertyChanged?.Invoke(args);
    }
}

new Collection { 1, 2, 3 }

Collection t = new();
t.AddRange(new[] { 1, 2, 3 });

ImmutableArray<int>.Create(new int[] { 1, 2, 3 });

[InlineArray(3)] struct __InlineArray3<T> { private T _element0; }

Span<int> __tmp = new __InlineArray3<int>();
__tmp[0] = 1;
__tmp[1] = 2;
__tmp[2] = 3;
ImmutableArray<int> ia =
    ImmutableArray.Create((ReadOnlySpan<int>)__tmp);

[MyPropertyGenerator] string? Location
{
    _location = value; //Или лучше "field = value;" - в C# уже обсуждают ключевое слово "field"
}