Personally I give each character a face, either from a person I know who matches their personality or a celebrity that fits the description, even though sometimes it can be really annoying if the author gives more details on the persons appearance and my character doesn’t fit that lol. I’m very curious as to what other people do.
Most of the times I picture the character as If I could only see their back. I see thier outfit, complexion, hair, even I can imagine their voice, the way they move and the way they smell (if it’s well written). But I’m unable of imagining a face, if it’s described in the book I can only picture the parts of the face separately.