It entirely depends on the culture around it. Is everyone expected to model underwear for their store? If someone doesn’t want to - is the culture supportive, neutral, dismissive, or antagonistic? Are they expected to do it but just allowed to choose not to? Or is there no expectation to do it, but volunteers are welcomed?
I can’t imagine anyone is being forced to, but it wouldn’t surprise me if the company culture is dismissive or demeaning of people who would rather not.