Question: can the byakugan turn into the sharingan?
Answer: Byakugan doesn't turn into Rinnegan , Mangekyou Sharingan does ! The requirement for awakening Rinnegan are both Sharingan and Hashirama's blood ! The Eternal Mangekyou Sharingan can be evolved into Rinnegan through combination of Ashura and Indra's Chakra , Basically replicating Hagoromo's Chakra.