Is "可以来 (ke3 yi3 lai2) ..." an idomatic way to say "please bring me ..."?
It is a euphemistic way to say so, as it would seem more polite.

We would use subjunctive mood/subjonctif to translate this expression, as "Could I have..." or "Puis-je avoir...". Note that this is always in the form of a question, so please do not forget to add "...吗？" in the end.