In order to create restrictions—and ensure your children can’t easily turn them off—you’ll need to turn on passcodes in your iPhone settings. The passcode will need to be input to access the Restrictions settings.
To create a passcode, go to Settings > General > Face ID & Passcode (or Touch ID & Passcode). Create the passcode you want and you’ll be all set
To access the Restrictions app, you’ll need to open your Settings and go to General. In there, you’ll see an option for Restrictions. Once you tap it, the software will request you input a passcode. Do that and you’ll see a long list of restrictions.
First things first, decide whether you want your children to access built-in apps, including Apple’s Safari browser, the Camera app, and FaceTime. You can also decide whether iTunes and the ability to install apps should be turned on. If you don’t allow apps to be installed, only you will be allowed to install programs when you turn off the restriction and install apps from the App Store
If you’ve decided to allow your children to download apps but want to restrict what they can access, scroll down on the Restrictions menu to the “Allowed Content” section.
If games is the real problem you’re dealing with, Apple makes it easy to control that behavior.
If you scroll the bottom of the Restrictions menu, you’ll see a “Game Center” section. There you can decide whether your kids should be allowed to play multiplayer games or communicate with others inside a game