You are too fast, mate.
I'm not sure I understand why you want to use them though, you should be able to use P2SH addresses (starting with 3) everywhere.
I have been using native segwit all these days & sometimes nested segwit as well; very few times, I have used Legacy. Nevertheless, I guess there's nothing wrong to know how I can get Legacy addresses on Bitcoin Core as I couldn't figure it out myself. That's the purpose; nothing else, mate. I was wondering why the hell Legacy wasn't there. Hence I'm here with this noob question.
Appreciate your help.