en_tn/gen/19/31.md

The firstborn ... the younger

Here "firstborn" and "younger" are nominal adjectives that refer to Lot's two daughters according to their birth order. Alternate translation: "Lot's first daughter ... Lot's last daughter" or "The older daughter ... the younger daughter" (See: rc://en/ta/man/translate/figs-nominaladj)

to lie with us

These words are a euphemism for sexual relations. (See: rc://en/ta/man/translate/figs-euphemism)

according to the way of all the world

Here "the world" stands for the people. Alternate translation: "as people everywhere do" (See: rc://en/ta/man/translate/figs-metonymy)