@Ana_B, Please note that the
'TabIndicatorHeight' property in the Top Tab Navigator does not actually adjust the height of the Tab Navigator. It just adjust the hight of the portion of the tab that shows you which tab is currently selected.
As for why the
'TabIndicatorHeight' property exists for the Top Tab Navigator but not the Bottom Tab Navigator, that is a limitation of the third-party library that we use to implement the navigators. My guess is that that library provides different capabilities for top and bottom navigators in order to support a consistent cross-platform look and feel which abides be the Android and iOS standard styles.
I hope this helps.