libffi can be imported via CMake FindPkgConfig module:

    find_package(PkgConfig)
    pkg_check_modules(LIBFFI REQUIRED IMPORTED_TARGET libffi)
    target_link_libraries(main PRIVATE PkgConfig::LIBFFI)

vcpkg provides proprietary CMake targets:

    find_package(unofficial-libffi CONFIG REQUIRED)
    target_link_libraries(main PRIVATE unofficial::libffi::libffi)