My friends and I are doing this silly thing where the three of us redesign two of the Mane 6, and I got the pegasisters (Fluttershy and Rainbow Dash)
Fluttershy is my favorite of the Mane 6, so I did her first!

I imagine she'd wear cottage-core clothing mixed with simple Lolita-style clothing. Stuff with frills and lace, but very simple and easy to move in. She wouldn't wear makeup, but her lips and cheeks would be naturally pinkish.
(I also gave her green eyes, since they matched her clothing better!)

(My friends don't have Sheezy accounts, yet, so I can't tag them, but I'll add links to posts they make about their respective redesigns on other platforms if they do post them)