Capacitor-Android add a view dynamically to MainActivity

Capacitor
1

I need to insert a RelativeLayout in MainActivity either dynamically or in layout/main_activity.xml and use View.setVisibility() to dynamically toggle the visibility of that View.

How can I do that ?

I tried adding a RelativeLayout to layout/main_activity.xml but in MainActivity the code is unable to find that using findViewById(R.id.darkscreen);