Hello! According to the Oxford Advanced Learner's Dictionary, 'get off with' means 'to receive no punishment', and 'get away with'  has a close meaning. For example, ''You won't get away with it next time!'' (Next time you won't manage to avoid the punishment), or  '' She got off with a small fine' (She avoided receiving the highest punishment.) I think it is clear to you. If you have any questions, you can consult  an online dictionary.