Yes you can but there are certain restrictions that Screen Time uses so it would be best if these were not changed:
- Rating Apps
- Game Center
- Safari
- YouTube
- iTunes
- Camera
- PhotoStream
- In App Purchases
- Assistant
- Explicit Content
To see Restrictions that help Screen Time run smoother check out this page.
Summary
Article Name
Can I turn restrictions back on after installing?
Description
Yes you can but there are certain restrictions
Rating Apps
Game Center
Safari
YouTube
iTunes
Camera
PhotoStream
In App Purchases
Assistant
Explicit Content