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.
Track made with Serum in the drop in the bass, chord and sub bass, for the lead part use a loop that cuts in some parts to make it sound unique.
Sample pack Dropgun Samples - East Future Trap
Loop name EFT_loop_melody_lead_pistons_140_E