You need to use the Android Native Development Kit (NDK), in order to compile the code into a static library . The bindings between the two layers (Android and C++ library) is handled via the Java Native Interface (JNI).
Can I use React Native with C#?
React Native for Windows supports writing native code in both C++ and C# , but there are trade-offs with each language. The choice of language can impact the compatibility, developer experience, and performance of your project.