plplot provides CMake targets:

    find_package(plplot CONFIG REQUIRED)
    # C API, PLplot Core Library
    target_link_libraries(main PRIVATE PLPLOT::plplot)
    # C++ binding
    target_link_libraries(main PRIVATE PLPLOT::plplotcxx)
    # wxWidgets GUI binding (optional, feature "wxwidgets")
    target_link_libraries(main PRIVATE PLPLOT::plplotwxwidgets)
    # CSIRO Cubic Spline Approximation Library
    target_link_libraries(main PRIVATE PLPLOT::csirocsa)
    # QSAS Time Format Conversion Library
    target_link_libraries(main PRIVATE PLPLOT::qsastime)