The package mapnik provides CMake targets:

    find_package(mapnik CONFIG REQUIRED)
    target_link_libraries(main PRIVATE mapnik::mapnik mapnik::json mapnik::wkt)
    
If you only need the compile definitions without any sources, use target mapnik::core.

If any plugins were installed, the variable ${MAPNIK_PLUGINS_DIR} contains the plugin directory
Fonts are available with the variable ${MAPNIK_FONTS_DIR}