How do I make my hoodie smaller?

I bought the gore core hoodie size M and the seller didn’t let my change it for another size after I bought it, hoodie is not true to size it’s oversized asf so how do I make it smaller?

I bought the gore core hoodie size M and the seller didn’t let my change it for another size after I bought it, hoodie is not true to size it’s oversized asf so how do I make it smaller?