app.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net5.0</TargetFramework>
    <Nullable>Enable</Nullable>
  </PropertyGroup>

</Project>

Program.cs

using System;

Console.WriteLine("Hello World!");

And if you want to access command line arguments, args is available as a "magic" parameter.
— https://devblogs.microsoft.com/dotnet/c-9-0-on-the-record/#top-level-programs

Thanks @qbit86.

@pmunin @contact4manoj See https://github.com/kzu/SmallSharp :)