magick *.JPG -resize 120x120 -set filename:base "%[basename]" "test-%[filename:base].jpg"

https://gist.github.com/ivince/429d9d49e76a36bb791641e3418ee347

magick *.JPG -resize 120x120 -set filename:base "%[basename]" "%[filename:base]_small.jpg"

https://imagemagick.org/script/command-line-processing.php

Finally to convert multiple JPEG images to individual PDF pages, use:
magick *.jpg +adjoin page-%d.pdf

magick identify P4151755_small.jpg
P4151755_small.jpg JPEG 120x90 120x90+0+0 8-bit sRGB 45872B 0.016u 0:00.002

magick -density 150 regulativy.pdf regulativy.jpg