Since there is a lot of artist making fanart of other artist’s OC, is it possible to use artist as a copyright tag? And yes I’m new here

Tag with original and borrowed_character, then (if you want to) leave a comment about who's character it is. We only tag artists if they did work on the image.

If OCs appear more than a few times in other artists’ works, they get their own tags. If the name is sufficiently individual, it’s fine by itself. If the name is less creative, possibly just a first name, the creator can be added as a qualifier, like ocname_(creator). If the character doesn’t have a name, use some creative description and a creator qualifier (like office_lady_(eu03) or ahoge_girl_(23)). The character tag should have a wiki that mentions the original creator.

See original and the list of original characters.

Also what fossilnix said.