I ordered a plush for someone as a birthday present from amazon. When it arrived it was in a hermetical package and felt like rubber. After opening it, trying to solve the problem by hand and letting it sit for 20 minutes it's still very wrinkly. What can I do to solve this issue?
Any time I have received a plush toy in a sealed plastic bag (which is generally how they will ship), the bag itself has been labelled with instructions to shake the toy after removing it from the bag to "fluff it up" and "make it look its best on the shelf." As you only specified "letting it sit," try giving it some really good shakes to see if that helps.
If the plush fabric still looks very wrinkled, and it's not a poor-quality plush, try using a soft brush to give it some additional fluffing and even out the pile of the fabric. If the "wrinkled" property you're describing is uneven stuffing, try fluffing it like a pillow to redistribute the stuffing and even it out.
Unfortunately, many popular character plushes on Amazon are poor-quality counterfeits, and it is also possible you've received one of these and there will be little to do to fluff it up. These are cheaply produced from low-quality materials, and often can't be made to look good at all.