If it works for the character, sure. It's boring to think everyone sounds exactly the same.

Right now, one of my main characters has a pseudo British accent that's a bit different from anything on Earth on account of it being a regional dialect of a planetary colony, and I have an NPC in another game that a fantasy pseudo-British accent on a much more crude and improper way, chiefly substituting my with me in sentences, among other things.

Most of my characters have a distinguishable accent, but it's usually not reflected in their dialog past the occasional slang term, but that's more cultural.