NoTuple.cs

void Main()
{
    var lb = new Vector2(1.1f, 2.2f);
    var rt = new Vector2(5.6f, 3.4f);

    ToCeilAndFlooredBoundingBox(lb, rt);
}

public static (Vector2, Vector2)  ToCeilAndFlooredBoundingBox(Vector2 lb, Vector2 rt)
{
    return (new Vector2((float)Math.Ceiling(lb.X), (float)Math.Ceiling(lb.Y)),
    new Vector2((float)Math.Floor(rt.X), (float)Math.Floor(rt.Y)));
}

// zatsu
public struct Vector2
{
    public float X;
    public float Y;
    
    public Vector2(float x, float y)
    {
        (X, Y) = (x, y);
    }
}

Tuple_Deconstruct.cs

void Main()
{
    var lb = new Vector2(1.1f, 2.2f);
    var rt = new Vector2(5.6f, 3.4f);

    ToCeilAndFlooredBoundingBox((lb, rt));
}

public static (Vector2, Vector2)  ToCeilAndFlooredBoundingBox((Vector2 lb, Vector2 rt) tpl)
{
    // deconstruct
    var (l, r) = tpl;
    return (new Vector2((float)Math.Ceiling(l.X), (float)Math.Ceiling(l.Y)),
    new Vector2((float)Math.Floor(r.X), (float)Math.Floor(r.Y)));
}

// zatsu
public struct Vector2
{
    public float X;
    public float Y;
    
    public Vector2(float x, float y)
    {
        (X, Y) = (x, y);
    }
}