Man pages matching name curlinfo_pretransfer_time in section 3:

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