I promise I don’t want you all to get my wrong, but the question came to me because I saw that AutoCAD lets you offset a line, I think you need to specific the orientation and the distance. I’m not using AutoCAD, only SketchUP, I understand they’re different and I understand some features can be considered more logical than others but that made me wonder if SU also lets me do it and I didn’t know how to, that’s all.
EDIT:
PS: I’m happy with SketchUP and I’m not looking for all AutoCAD features, I just wonder if some of them are in SU I didn’t see so far.
Interestingly, neither flip or offset need faces. They both work fine if there is more than one line. Needs to be connected lines in the case of offset.