Some examples:
"Children aren't meant to be working in factories; they should be in school!". I thought "子供たちが工場なんて所で働くのは子供っぽいじゃない" or ”〜で働くべからず。”
A: "Today I filled everyone's water bottles in the office!"; B: "Uh, you're not really meant to do all that.". I thought "そういうことじゃ、役割にはないだろう" or some such usage of 役割.
I think the connotation in the above in the usage of 'meant to be' is along the lines of "You, as a student or an office worker or a child, or whatever, have this pre-ordained/socially established set of things you ought to be doing but you are doing things that veer off this course."
Are there more general ways of conveying this in Japanese or is it highly context dependent?