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.
bass and synths are midi with one shot samples or sliced loops in simpler
Sample pack Samplestate - Little Helpers Minimal Tech and Deep Vol 3 MULTiFORMAT
Loop name ssl lh synth chord loop 123 13 dm