Ref. No. 1149/42-374
In the name of Allah the most gracious the most Merciful
The answer to your question is as follows:
Singing Dua like a song is not allowable, but if one beautifies his voice in dua while he is sincere in it, then it will be permissible.
And Allah knows best
Darul Ifta
Darul Uloom Waqf Deoband