Man pages matching name gnutls_db_get_default_cache_expiration in section 3:

gnutls_db_get_default_cache_expiration.3.en	debian 10 / gnutls-doc
gnutls_db_get_default_cache_expiration.3.en	debian 11 / gnutls-doc
gnutls_db_get_default_cache_expiration.3.en	debian 12 / gnutls-doc