How are sketches like this drawn?
One way I think is common among comic artists is through instancing*: after having drawn a few of the figures in different positions, you can copy instances of these individual figures unto the panel using either

a lightbox or light table, when working with traditional tools, or

image editing software (e.g. Photoshop or Clip Studio Paint), when taking a digital approach.

Alternatively, some specialized software allows for importing 3D models that can be positioned, after which a render can be made that looks like a drawing.


However, at close inspection, this particular image doesn't show obvious signs of instancing, so I think this was all drawn by hand by Kishimoto.
That, or the instances were edited afterward (using any of the approaches mentioned).

* I'm not sure 'instancing' is the term used in the comic world, though: I know it from 3D editing software and game engines, where it is common.