Man pages matching name curlopt_ssh_public_keyfile in section 3:

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