Man pages matching name encode::tw::unisys::sosi1 in section 3pm:

Encode::TW::Unisys::SOSI1.3pm.en	debian 10 / libencode-hanextra-perl
Encode::TW::Unisys::SOSI1.3pm.en	debian 11 / libencode-hanextra-perl
Encode::TW::Unisys::SOSI1.3pm.en	debian 12 / libencode-hanextra-perl