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.
For melodies made from scratch I've used Serum and Keyzone Classic. Also, on some parts of beat I've used flute loop. Drums are completely made from one shots without any loops.
Sample pack Splice Originals - Dark Treasures: Southern Trap
Loop name SO_DT_140_flute_magnolia_Abmin