In general, lines like these are generally done in the composition phase (撮影).
It would lead to problems when sending douga overseas (like almost all douga is these days).
One Piece's current Wano arc's lines are also handled in composition.

When stuff was done analog, douga would straight up be burned (I don't know the technical terms here) onto cels, leaving the actual pencil lines, and thus more of a hand-drawn feel like the examples you posted. (The process is at 14:20 in this video https://www.nicovideo.jp/watch/sm5738253 )
Since its all digital from 仕上げ onward now, lines have to be aliased because using the color fill tool with anti-aliased lines is unnecessary work when coloring. Any effects are applied only when it comes to composition stage.