Rapunzel never had a phone (or electricity) before Darrow, so the standard phone that was given to her is more than enough for her. She probably has it in a pink sparkly case, and the wallpaper changes a lot. It's usually Pascal, or a selfie with her and one of her friends. She often forgets to charge it, and calls people a lot because to her, it's easier than texting.

She probably has all sorts of games on her phone, and never deletes any photos. She has to get someone to help her with it all of the time. (Sorry, Rapunzel's friends.)