PipeTest/Parent/Parent.csproj

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

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net5.0</TargetFramework>
    <RootNamespace>PipeTest</RootNamespace>
  </PropertyGroup>

  <Target Name="PostBuild" AfterTargets="PostBuildEvent">
    <Exec Command="copy $(SolutionDir)Child\$(OutDir)Child.* $(TargetDir)" />
  </Target>

</Project>