Du'a for children's beautiful character

اللَّهُمَّ كَمَا أَحْسَنْتَ خَلْقَهُمْ فَأَحْسِنْ خُلُقَهُمْ

Allahumma kama ahsanta khalqahum fa'ahsin khuluqahum

O Allah, just as You have made their physical form beautiful, make their character beautiful.

Adapted into the plural for children from Musnad Aḥmad 24392.