How to better design the cPP class

in the previous definition of a class, it is generally the structure of a base class (virtual base class or pure virtual base class) plus a derived class.
the veteran programmer told me that like Microsoft COM, we should first declare some interface classes (mostly set,get methods). The base class inherits these interface classes, and the derived class of the base class can inherit some other interface classes that implement interface methods that are different from the base class.
it makes sense to think about it this way, but is it too many interface classes to design this way?
want to see the structure of COM, but it is not open source. Do you have a boss to explain it

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CPP
Mar.12,2021

recommend the design pattern column written by @pezy boss.

Design pattern

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