// C# 8

var a = new[]
{
    new Foo(1, 2, 3),
    new Foo(1, 2, 3),
    new Foo(1, 2, 3)
}

// C# 9

var a = new Foo[]
{
    new (1, 2, 3),
    new (1, 2, 3),
    new (1, 2, 3)
}