Inspired by Roman style, observe type of column behind.
In the past resources (artistic poses, anatomy displays and figural ideas ) didn't exist.
The painter had to look at ''something'' to draw, or paint so often it were statues of past times.
If lucky courtesans, prostitutes or servants would be used to pose.
Ignoring accurate commissioned works for Popes and similar.
Your dress style example:
Da Vinci's Salvator Mundi.
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Niobe:
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Her facial expression is often used to portray a repentant Mary Magdalene.
Juno:
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And the variations of her were used as every shepherdess Arcadian or otherwise.