Sexual Idiom is Plain

The Hebrew verb yada, to know, has a wide range - it can mean acquaintance, recognition, understanding. Some readers have used that range to argue the men of Sodom only wanted to interrogate the visitors.
Verse 8 closes that door. Lot describes his daughters as women who have "not known any man." Same verb, three verses later, in a sense nobody disputes. The narrator has settled the question inside the passage.
Worth keeping two things separate, though. This establishes what the mob was demanding. It does not settle what Jude means centuries later by "other flesh" - that phrase turns on a different word, and Jude's argument is about the kind of being the visitors were.
Scripture links:
- Genesis 19:5 - "bring them out to us, that we may know them."
- Genesis 19:8 - "two daughters who have not known any man."
The text defines its own terms. It just does it three verses after you wanted it to.