Sentence examples for that person from inspiring English sources

The phrase "that person" is correct and can be used in written English.
It is often used to refer to a specific person who has already been mentioned or is easily identifiable in the context of the sentence. Example: "I can't believe that person stole my wallet! I was standing right next to them at the cash register." (In this sentence, "that person" is used to refer to the individual who stole the wallet.).