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.
Classic Arp 2006 and ambient pad.
Instrument FX and percussion loop
Sample pack Splice - Nik Dean Sample Pack 24 44.1,
Loop name NIK_DEAN_fx_loop_back_to_future 91