I don't speak Ukrainian, so I can't judge what exact words Zelensky used. https://www.youtube.com/watch?v=uwUWidMCQ88

I do know that Biden has called for regime change in Russia multiple times - in English - and his staff walked it back just like Zelensky's did. I know that Biden told US soldiers in Poland that they'd see what the war is like when they get to Ukraine. Also walked back.

Granted, Biden is semi-senile, but he's said enough and had it walked back enough that I can fuly believe it is possible that Zelensky called for first strikes. I don't know an independent Ukrainian speaker to give an objective translation.