Impossible to tell from behind.
She looks probably just a bit smaller than one of my EXs whom I met when she was 32 and I was 21, by the way, and all the jokes were on her for picking a "young boy." Haha.
But I ain't as tall as that guy; my EX was up to my shoulder.
I did, however, see her pic with tall farang guys and the size difference looked ridiculous.