The base is original from the producer (chords and melodies), but is complemented with elements that complement the song that come from samplepacks, usually, vocal chops, guitars, wobbles sections, glitch effects. It is the standard in which most of producers work, in a project you will find MIDI files made by the producer, but also melodic loops.
Melody downloaded from the looperman for free use. I used the classic 808 spinz and just distorted it to make it stronger
Sample pack Looperman
Loop name Southside X 808 Mafia