Do you think Carla would ever style her hair differently from her usual hairstyle? (Personally I think she will ☺)
Yes of course! I'm sure she'd experiment with different hairstyles, especially during different festivals now that her life will be a bit more relaxed (And technically she already has tried out a different hairstyle when she was Rita, but that seemed to be more the potions doing anything else).
As for what style she might try... well she'd probably still use a lot of ribbons in her hair, because those seem to be part of her style. But maybe a style where her hair is down a bit more? (Or if Elena is going always wear her hair up now that she's queen she could always try the single ponytail look).