C# at least supports the notion of partial classes that can have their definition spread over multiple files: https://learn.microsoft.com/en-us/dotnet/csharp/programming-...

Ruby has mixins and Python supports multiple inheritance. Go encourages composition over deep nested hierarchies.

Many main stream languages support this kind of functionality.

Superclasses, interfaces, or module import. I'm no Java or C# expert but you have to lean into the conventions the language provides. I would probably have a separate small POJO that stores the configuration for the class if it had so many getters/setters I wanted to split them out.