There is an individual on Youtube with I believe nearly 9" wrists that was already genetically gifted. This person however also has grown his wrists over time and has lots of content on it. Take a look at this video, where he specifically discusses Wolff's law: https://www.youtube.com/watch?v=kZ0G_kpEbvY
He has many other videos for wrist and forearm training. He also discusses some anecdotes of tradesmen that use hammers to hit things all day and hypothesizes the vibrations in the bone of the wrist and hand can thicken these bones.