I do indeed! Fear State is compiled for your convenience here.
I broke down Lex Luthor’s first encounter with Supergirl in this post, from 2019:
As for when they started hanging out, Supergirl- or, at least, some version of Supergirl- would actually date Lex Luthor for some time in the 90s, during a point when Luthor was masquerading as his own long-lost son. Their relationship would begin in Superman: Panic in the Sky.