android – Change textSize of BottomNavigationView item

Why does BottomNavigationView have XML attributes like itemTextColor but noitemTextSize?

J & # 39; would:

A) Change the default text size of each element of my background navigation

B) Change the text size of an item after being clicked (ie how can I access the text size in onNavigationItemSelected ()?

The reason I ask the question is because I try to prevent having a selected element at first (the default is that the first element is checked):

replace fun onCreate (savedInstanceState: Bundle?) { (0) .isCheckable = false

replace fun onNavigationItemSelected (element: MenuItem): Boolean {
item.isCheckable = true
returns true

However, the code above only prevents the first item from being checked. Color. He always checked text size (a little bigger than the uncontrolled text size).

An idea of ​​how I can solve this problem?