Bismihi Subhanahu Wa-ta'ala
Assalamooalaikum Warahmatullahi Wabarakatuh

In principle, it is permissible for the father to bathe his daughter just as it is for the mother. The laws of modesty do not apply here as it is a necessity, for the children are dependent on their parents especially at this young age. As they get older and develop understanding, it becomes more and more necessary to be cautious in this respect. In any case, the laws of modesty should be inculcated even from a young age.

And Allah knows Best,