Man pages matching name curlopt_postfieldsize_large in section 3:

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