“I’ll See You Out” Means “I’ll Walk You to the Door”

When a guest is leaving, a host might say, “I’ll see you out.” This means “I’ll walk you to the door”, not “I’ll meet you outside”. The phrasal verb see someone out describes accompanying a visitor to the door or exit, giving the visit a polite close.

A: Thanks for having me. I’d better get going.
B: Of course. I’ll see you out.

It differs from see someone off, which often means going to an airport, station or another departure point to farewell someone. If you genuinely mean meeting outdoors, say, “I’ll see you outside.” The expression is natural in Australia and Britain; the important point is to understand see someone out as a whole rather than word by word.

https://dictionary.cambridge.org/dictionary/english/see-out