@ValidX i know about using models as reference*
tracing is practically stealing work and its heavily frowned upon, most mangaka [insert Toyotaro and Togashi]
taking inspiration is another thing.. like how Horikoshi took inspiration from a Spiderman Cover to make something entirely different
what i'm referring to though are djs who's art style are somewhat inferior deviations of the character sheets from Dragon Ball Super (forgot the guy's name)
or Toriyama's style, who randomly draw suspiciously close to whomever they are seeking to imitate
till you find out they totally traced several panels/ screenshots making a 1 to 1 copy, and transferred it into the context of their story.
i don't think this is what you had in mind, so i'm just clarifying