The lead voice sounds clean with a little echo or reverb. They may have just shot it in a large room. I don’t think it’s vocal doubled or anything fancy like that. You may need mild compression to keep the expression out—to make it sound flat. It’s a rap track, not grand opera.
The backing track is heavily produced. I don’t even begin to guess all the things they did to that.
It’s stereo-reverb on the vocal & the acoustic bass, so my money is on it being an reverb-effect, rather than a real room.
The reverb effect on the vocal is quiet in the mix, but it has a very-long reverb-time : the reverbed words are blurred beyond recognition, (so somewhere between Cathedral and Church-hall).