I think Lady Sarah Chatto is so consistently stylish and timeless in a low key way that if princess Charlotte ends up taking after her she'll be well set for life (superficially speaking).
I also think now that prince George is getting a bit bigger that there are Windsor bits starting to appear in his face.
The children will be more visible now because their parents are more visible, and will have had time to get comfortable with the idea of how and when to be visible as a family. And regardinh clothes I suspect it is s mix of "work" and "not work", and possibly personal preference on Charlotte's part, she must have opinions by now and I suspect isn't shy about stating them. That said, there were jeans in the clapping video and probably often is at home.