Man pages matching name curlopt_new_directory_perms in section 3:

CURLOPT_NEW_DIRECTORY_PERMS.3.en	debian 10 / libcurl4-doc
CURLOPT_NEW_DIRECTORY_PERMS.3.en	debian 11 / libcurl4-doc
CURLOPT_NEW_DIRECTORY_PERMS.3.en	debian 12 / libcurl4-doc