Welcome back to the Disney Parks Moms Panel, Tiffany!
Thank you so much for bringing us your excellent question! To my knowledge, you are the first to inquiry about this option; with the growing number of 3D attractions available, it's definitely a valid concern. After doing a little research and reaching out to Cast Members I have learned that 2D glasses are not available. You have brought up an excellent point with sensory issues and I will be passing along the suggestion to our guest services team.
I do want to offer a few tips that may help with the 3D attractions available at Walt Disney World® Resort - even I get a little disoriented on some of them.
Mickey's PhilharMagic in Magic Kingdom - This is one of my favorite attractions of all-time and luckily this "show" does not give me any trouble at all. I do think this would be a great one to try first to see how your prince charming and princess react.
Muppet* Vision 3D in Hollywood Studios - This is another show and another great starting point.
Star Tours - The Adventure Continues in Hollywood Studios - For sensory issues, I do not recommend this attraction - it's a lot to handle, even for me. Not only is it 3D, but there is a lot of jerky motions as the seats move around like a simulator. I still ride it because my children enjoy it, but I usually have to close my eyes a lot.
It's Tough to be a Bug in Animal Kingdom - 3D show available in the Tree of Life.
Flight of Passage in Animal Kingdom - This is Disney's newest 3D attraction and it's amazing! This attraction is the most immersive, but doesn't bother me as much as Star Tours.
I hope these tips help, Tiffany! Please let me know if you have any additional questions. I am here to help.
Faith