You typically use compression (heavy), parametric eq, de-essing, subtle delay for rap vocals, panning, sometimes reverb, pre-verb, but you can also use vocoders, wahs, chorus, flangers/phasers, pitch-shifters, pitch-correction, distortion, etc. if you like.
You can also comp vocals from different takes, double-track and layer vocals, add whisper tracks, room/live clips, but those are tracking/mixing techniques, and not effects.