Shortcode to show latest post from sub-category

Shortcode to show latest post from sub-category.I have a category called Announcement with the sub-category called 2018 so it will be like this:

Announcement

2018
2017
All the files this year I will add in 2018 sub categories and I will create another sub category call 2019 next year.

My question is if its possible to show the latest file in the sub-categories using shortcode for the parent?

Announcement id is "29" so I want to show all the latest files that is in sub-category which is currently in 2018

Currently, it will only the files in Announcement but not the sub-category. It be nice to be able to show all the lates files from the sub category just by using the parent id/