Wearing costumes at Disney if you are an adult and it’s not a special event is EXTREMELY frowned upon. If you can tone it down into a disneybound then that’s better. Disney is private property and if you are causing too much attention and acting like the character, signing as them, meeting as them… they can ask you to change clothes and or ask you to leave.
You might not get treated as generously by the cast members as well as CMs don’t like costume wearing guests either because it ruins the magic. You do not want unknowing guests to mistake you as a character. If the parents have to tell the kids “oh that’s not Ariel” when they are at Disney. What are they gonna think when they meet the real Ariel, they might have doubts. That is where you have ruined the magic of it and their belief.
Also remember that not every adult is knowledgeable on cosplay. They can’t tell the difference either when at Disney. It’s your responsibility as the cosplayer to not cause the confusion at Disney and not crush the imagination of children.