Man pages matching name tcpclient in section 1:

tcpclient.1.en	debian 10 / ucspi-tcp
tcpclient.1.en	debian 10 / ucspi-tcp-ipv6
tcpclient.1.en	debian 11 / ucspi-tcp
tcpclient.1.en	debian 11 / ucspi-tcp-ipv6
tcpclient.1.en	debian 12 / ucspi-tcp
tcpclient.1.en	debian 12 / ucspi-tcp-ipv6