To style the tab navigator you have the tabBarOptions prop
use labelStyle to style the label and tabStyle for tabs etc.
to make the text appear in 2 lines you need to set the label width or add padding
to add a line below the active tab use indicatorStyle as in https://stackoverflow.com/a/47025116/13196047
these options are just an example, you need to customize them to your style...
const options = {
style: { height: 36 },
labelStyle: { fontSize: 12 },
tabStyle: { marginTop: -5 }
indicatorStyle: { borderBottomColor: 'white', borderBottomWidth: 1 }
}
<Tab.Navigator tabBarOptions={options} >
<Tab.Screen name="CropDetail" component={CropDetail} />
<Tab.Screen name="SoilReport" component={SoilReport} />
<Tab.Screen name="SomeOther" component={Component} />
</Tab.Navigator>