I think the picture in the initial post exaggerates Brienne's height just a bit.
While she is certainly a tall lady, she is not THAT much taller than average. (See notes from Wikipedia below).
Gwendoline Christie (born 1978) is an English actress and model. She is known for portraying the warrior Brienne of Tarth in the HBO fantasy-drama series Game of Thrones,
Christie's striking height, 6 ft 3 in (1.91 m),[4] attracted the attention of photographer Polly Borland, who made Christie the subject of a noted series of photographs, entitled Bunny, between 2002 and 2008.[11] According to Christie, she felt then that the photographs—in which she appears mostly nude—could help her come to terms with her body, and challenge notions of femininity. However, she later said that she was shocked in retrospect that she had agreed to them.
Scoliosis is curvature of the spine.
Look closely at her vertical alignment and the height of her hips, left to right.
Her shoulders are even, but her hips are out by a couple of inches, at least.