There are different types of Rayon but generally yes, it does wrinkle. It's a cellulose fiber like cotton and it will easily wrinkle like cotton does. It also depends on the weave, type of rayon, blend of other fibers in the fabric and the type of finish added to prevent wrinkles (like permanent press).
The patterns on them and the style they are cut.
see what size you are and then go in the dressing room and try them ondut if they don't have a dressing room then go home and don't rip the ta of and see if they fit. if they don't then take then back and purchess a new pair you think a going to fit and do the same thing but if the second pair fits then don't do the same ending bit.