Seems like she could reach a 11th with more stretch
If she's a woman it is indeed remarkable
Look at this page
https://www.dskeyboards.com/html/handsizepage.htmlYou can see that usual woman spans stop at 8,9 which is 22 cm or almost a tenth
So reaching a 11th would be very rare for a woman according to this table
Also let's not forget that piano playing increases our hand span
Gruffalo you wouldn't have those hands if it wasn't for piano playing
One reason is the growth stimulus during growth that increase the amount of cartilage that is turned into bone. Not many people know for example that playing basketball increases the final height of a growing kid or that a kid who plays baseball will grow with the arm he/she uses to throw the ball way longer than the other.
The other reason is the loosening of the web of skin between the fingers
Playing piano eventually lead a pianist to be able to position the thumb and pinky in a straight line. The still tight web of people who don't play piano don't allow them to do so