I'm not speaking in vague generalities here. New features in C# do not stop you from writing old C#, and they never have.

Here's code that uses the delegate keyword introduced in C# 2.0, twenty years ago. You'll rarely see an explicit delegate in a modern C# codebase, but the C# compiler is still happy for you to use it.

https://dotnetfiddle.net/l14cXD