Is the wife entitled to seek divorce based on the outcome of Istikhara prayer, given that the marriage contract has been concluded and the wedding date set?

If the legal marriage contract is concluded with all its conditions and pillars fulfilled, such as the offer from the guardian saying: "I marry my daughter so-and-so to you," and the acceptance from the husband saying: "I accept her marriage," and with the testimony of two just witnesses, then the paternal cousin becomes his wife legally. He is not obliged to divorce her on the pretext of her performing Istikhara, rather Istikhara is not prescribed for her in this matter, and it is not permissible for her to seek divorce except out of necessity.