Microsoft usually provides decent code samples when it comes to new language features although sometimes the code samples provided are not relevant to real world usage. For this reason i have started a GitHub repository for new C#9 language features couple with a few C# 8 language features.

There are two projects, both use .NET 5 Framework.

GitHub repository

Microsoft docs
new operator (C#9)
Recursive Pattern Matching (C#8/C#9 added use of switch)