"Right dislocation" construction in English

Hi, and welcome. American native speaker here. I never use pattern 2). I hear it from British English native speakers sometimes, though. Not often. As far as I can tell, it's used to emphasize either the truth of the statement or surprise at what happened. A BrE speaker can give you a better answer, I think.

Thank you for reply.
I will take varieties of English, such as American English and British English, into considertation.

No sweat. Yeah, even within the US and England, there are strong regional variations. I imagine it's the same in China, eh?

Sure. Mandarin Chinese has its varieties. I'm from Taiwan, where Taipei 101 is located.

Heard it from Yoda, we have. (language students please disregard)

Additional phrases added for emphasis are certainly readily understood in BrE. These parentheticals, tacked on to the ends of sentences, have the same role as the markers used to declare truth or strong intent, emphasise or focus e.g. 'truly' or 'in truth' or 'the facts of the matter are' which are usually put before the main sentence.

She hit me, she did!
I heard him say it, I did!
I'll eat all the cakes, I will!
I'll report him to the police, so help me God!/you see if I don't!/etc

I think it is chiefly regional/colloquial/conversational; it is a cliché that Northern Irish people say "so I did", "so he would", etc after an utterance. People from the North West of England might say "It is very warm, is our house" I am doubtful that such forms are confined to BrE though; I am sure that some N American colloquial forms have them.