Because C++ has been used in so many different domains and for so many decades(!), there are an overwhelming variety of architectures that have been deployed to

Because C++ has been used in so many different domains and for so many decades(!), there are an overwhelming variety of architectures that have been deployed to great success in their own problem space. So I think you'll have a hard time finding resources until you narrow down what sort of things you'd like to be designing. You can spend years learning all about great design patterns that make sense for an IoT or embedded system but have completely backwards ideas about how to organize code for a game that needs to process 1000 unit movements per frame. But once you figure out some narrower domain that you like, you should be able to find books about it , (if you're good at reading code) can start studying open source approaches to it, and can start prototyping small projects to gain some hands-on experience and muscle memory.