It may not be expected, but it's definitely hoped for that you can at least make something that isn't going to make your eyes bleed.
The nice thing is nowadays Bootstrap (maybe with a decent theme like Flat UI or Ace Admin) will get you 90% of the way there. Very basic design knowledge will get you the other 10%, and for anything past that you can hire a designer.
There's 'design' and there's 'graphic artist' - sorry for the semantic distinction. There's a lot of basic design you can get from BS or foundation or whatever, and themes and such that all look nice. Coming up with specific artwork to match it (logos, something beyond just typed fonts, etc) is something I classify more as 'graphic art' work vs 'design'. It maybe be a distinction without much of a difference to some, and maybe there's a better way to phrase it, but it's a moderately important distinction in my head for some reason.
The nice thing is nowadays Bootstrap (maybe with a decent theme like Flat UI or Ace Admin) will get you 90% of the way there. Very basic design knowledge will get you the other 10%, and for anything past that you can hire a designer.