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.
The only melodic loop used is the vocal chops. Bass from Serum
Instrument Vocal Chops
Sample pack Variavision Soulful & Tech House Vocals 2
Loop name STCHV2_Vocal_61_123_Dm