mongo-cxx-driver provides CMake targets:

    find_package(bsoncxx CONFIG REQUIRED)
    target_link_libraries(main PRIVATE $<IF:$<TARGET_EXISTS:mongo::bsoncxx_static>,mongo::bsoncxx_static,mongo::bsoncxx_shared>)

    find_package(mongocxx CONFIG REQUIRED)
    target_link_libraries(main PRIVATE $<IF:$<TARGET_EXISTS:mongo::mongocxx_static>,mongo::mongocxx_static,mongo::mongocxx_shared>)