Man pages matching name curlopt_dns_cache_timeout in section 3:

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