1. Launch the Settings app on your iPhone and tap Safari from the list of options.
2. Now scroll down and tap Extensions.
3. You may already have some extensions installed in which case this is a good chance to view them and turn them on and off. Otherwise, tap More Extensions to find and add more.
4. You will be taken straight to the App Store, which will land on the Safari Extensions page. Browse the extensions and tap Get next to the ones you like.
5. When prompted, tap Install and enter your Apple ID password if asked.
6. The extension will now appear in the list of Allow These Extensions. However, you may find that new extensions are turned off. If so, simply tap the extension you want to turn on.
7. You can now tap the switch next to the extension to turn it on. You can also go through any list of permissions and decide what data the extension can access.
8. Extensions can also be managed in Safari itself. Simply tap the AA icon in the search bar and select Manage Extensions.