Apple version[0], Microsoft's take [1], related research by Google [2]. My Google keywords were 'smartphone keyboard dynamic touch targets' btw.

[0] https://www.cnet.com/news/iphone-keyboard-learns-what-you-ty...

[1] https://www.microsoft.com/en-us/research/wp-content/uploads/...

[2] https://static.googleusercontent.com/media/research.google.c...