How to convert the address start with "M" to an address start with "L"?

I tried to use the litecoin core to get a new address, but it’s start with “M”, is there a method to convert it to the address that is start with “L”?

thats not possible … thats a segwit address

Yeah you can’t do this. You need to contact the developers of the app you’re using and let them know that you’re trying to send to a litecoin segwit address, but your wallet/website hasn’t been updated.