Each particle random scale

Phaser 3
8

Try only

this.scene.add.particles('particles').createEmitter({
  x: { min: 0, max: 1000 },
  y: { min: 0, max: 1000 },
  scale: { min: 0.1, max: 0.9 },
  frame: { frames: ['cube_1', 'cube_2', 'cube_3', 'cube_4'] }
});