At this young stage, continuity is usually more comforting to little ones. So, I would use the same bedding, i.e. sheets, blankets from the crib, add in their fav plush pals and a comfy pillow. use their fav colors and or character theme if you need to upgrade bedding materials. It may help to have a bonding ritual at bed time to include their new space, like reading time together at bed time as well.

What are her interests (ex. favorite color or character)? You just need bedding and colors that appeal to her. Ask her what kind of bed/room she wants and then talk about how cool it is so she gets excited.

Pink = Princess Aurora (bed/room)

Teal and purple = Frozen

Red, yellow, blue = Snow White

Green and orange/coral = Ariel

Pink and purple = Doc McSuffins