Can we integrate multiple themes into one site

I am a beginner to Jekyll and I want to build my portfolio for technical writing using Jekyll. The portfolio should include both the samples: User Documentation and API Documentation. I saw there are themes available for API documentation and user documentation as well.

Is there theme that I can use for adding both of my samples in a single theme?

Thank you in advance.

I don’t think Jekyll can handle that itself, but most themes are just some css so it probably would not be too hard to hack one into another.