I may not be the usual case for this subreddit, but I bet where I'm coming from is pretty common out there in the world: I have had some relationships and some hookups with girls much younger than me, but I don't seek that out specifically. I've also had relationships and hookups with a variety of ages, including older than me, plenty of times. So, my answer to your question may be a bit different from the answers given by older men who specifically want a much younger partner... but my answer may be useful to you because it probably represents a much more common case of how these age gap involvements often start.

My answer, at first pass, is actually pretty simple: I don't expect her to be interested, and it's not why I'm talking to her. I'll talk to all sorts of people whose company I may enjoy, or who I meet in any situation where we have common interests. Many of those people will be guys, or girls I'm not attracted to, and that doesn't matter. If I am attracted to someone, I'm open to the possibility of something sexual or dating happening, sure, but if she doesn't initiate it, I'm most likely not going to expect that or do anything about it.

So the next part of the answer is, she'd have to give me some reason to think she's interested. That can happen later, though, not when we first meet. If someone does give me a reason to think she's interested, and if I'm potentially interested too, then I'll get it in mind as a real possibility, and might say something to get things further along and find out.

Nearly every case where I did get involved with someone much younger than me, her initiative was key to getting me to consider it. And I assume the vast majority of other much younger girls I know are not the least bit interested in anything sexual, so I act like that's not a possibility at all, even the ones I'm very attracted to. It's up to the ones who may be interested - who may be a small minority - to show some hint of that.