You can hide your future posts from people whom you do not know on Facebook. Just Follow the Below STEPS:-
1. Open Facebook.
2. A. Click on icon on the right corner of the screen.
B. Click on Settings and Privacy.
C. Click on Privacy Shortcuts.
D. Click on ‘Who can see my stuff?’
E. Click on ‘Who can see my future posts?’
F. Choose the option that best suits you like friends or public.