Estella goes to Richmond to live with a society woman so that she can show Estella off and introduce her to the social circles of the rich.
Estella tells Pip that he is going to have to escort her to Richmond, because the two of them must follow orders and have no will of their own. He asks what she will be doing there, and Estella explains.
“I am going to live,” said she, “at a great expense, with a lady there, who has the power—or says she has—of taking me about, and introducing me, and showing people to me and showing me to people.” (ch 33, p. 181)
Through this process Estella will become part of high society, because until this point she has mostly been tucked away at the creepy Satis House or in school learning to be a lady. Miss Havisham is continuing the next step of the plan, to expose Estella to more men whose heart she can later break. Estella should meet some young gentlemen and take them for a ride for a while, because Miss Havisham wants to use her as an instrument of revenge against men.
Pip does not understand Miss Havisham’s plan. He accepts his escorting Estella as part of their courtship. Since he assumes that Miss Havisham is his benefactor, he also assumes that she elevated him in order for him to be her equal. He has not idea that to her his role is just an added benefit.