What is the ruling on carrying the child of adultery (born in 1988, whom she has not seen since) and what is the expiation for that, knowing that she has repented with sincere repentance?

If a woman repents sincerely by abandoning the sin, regretting it, and resolving not to return to it, then Allah accepts her repentance and forgives all sins. Indeed, He replaces her bad deeds with good deeds, as Allah the Almighty says: "Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'" And His saying: "Except for those who repent, believe and do righteous deeds; for them Allah will change their evil deeds into good ones." And she should frequently engage in repentance, seeking forgiveness, and performing righteous deeds, for good deeds erase bad deeds. If her son finds her, she should seek his forgiveness for abandoning and neglecting him, for he is her son and has rights of motherhood.