Tricky SMTP settings question

On the PC version of Outlook 2021, there is an SMTP setting (under POP and IMAP Account Settings -> More Settings -> Outgoing Server tab) "My outgoing server requires authentication." If you check/tick that box, you get three choices: 1) Use same settings as for incoming mail, 2) Log on using...(and spaces for User Name and Password), and 3) Log on to incoming mail server before sending mail. I am not sure just what choice 3 does, but it MUST be chosen for me to send mail using an ISP domain (connect.com.fj) different than my current ISP (unwired.com.fj).

The problem: I cannot see any similar way to set up my iPad Mail. Unwired gave me the settings to use for SMTP (either relay.unwired.com.fj using Port 25 and no security, or mailrelay.unwired.com.fj using Port 587 and TLS). On my PC, those settings ONLY work if I also choose "Log on to incoming mail server before sending mail." Does anyone know a way to configure the SMTP server in iPad Mail with something equivalent to "Log on to incoming mail server before sending mail"?