How should I handle an uncomfortable message from an older person online?

Hi so I (16M) have been chatting online with someone older (19F) for about the past month or so. Keep in mind this was in reddit dms. Most of our conversations were normal — school, hobbies, movies, etc. But recently, she sent a message asking if I wanted to be sexual with her in a way she thought wouldn’t be “creepy, even while acknowledging I'm younger. I don't want to state any of the quotes for exact just to keep it safe. And I am also posting this from a fresh throwaway rather then my main just for safety. Just clarifying so you don't think I'm a troll. Will probably delete this account and post soon after.

This made me feel a changed vibe of our chats. Usually I enjoy talking to her but idk anymore. I’m unsure whether it's safe to just dodge the question and continue chatting or to stop responding and report. I don't want to overreact, nor let my guard down.

What should I do?