Question for buyers

I’m a Poshmark newbie, and just made my first purchase today. I carefully read all the information and measurements. My question is: what do people do if an item arrives and doesn’t fit? Do you post it yourself and try to sell it? The only reason I purchased the dress is because my daughter’s getting married, and her future in-laws are quite well off. I’m not, and I didn’t want to look like I crawled out of a dumpster behind Walmart. I never could have afforded the dress at full retail. Any suggestions? Thanks!