B12 won’t cut it. Curly toe issues are largely related to B2 deficiency. You can get B complex which has all the Bs at any pharmacy. I got B2 in a dropper bottle on line.
Curly toes in young chicks is quite likely to be due to vitamin B deficiency. Particularly if there isn’t anything else wrong with the leg.
If so, it is easy to solve with vitamin B supplements from the pharmacy. They are very safe so it is a good idea to try this anyway.
As @SilverBirds said...