No. Tonraq became chief after being elected years later. Sokka and Korra share no relation. Except Korra might be related to Yue, so if she is then they’re somewhat related.

I’m talking about Senna. Tonraq probably became chief because she was the chief’s daughter.

Tonraq was elected chief so no,

Where did we learn this?

Sokka and Katara are siblings...

Wait...I read it wrong...

No as he was elected chief at the end of the show, Senna couldnt be related to a previous chief as Tonraq would have been elected immediately otherwise. Also the official family tree does not show a relationship between Senna and a chieftain nor does Sokka have any known descendants.