Content blockers are extensions that let Safari block cookies, images, resources, pop-ups, and other contents. Content blockers affect what content is loaded while using Safari. If you want to make pages load as fast as possible, turn content blocker on is a good choice.
Before you enable content blocker for Safari on iPhone/iPad, you need to download a content blocker first app.
Go to the App Store to download a content blocking app. The best content blocker app available for iOS devices, like 1Blocker, Crystal and Purify.
Go to Settings > Safari. Scroll down to Content Blockers option, then set up the extensions that you want.
Tips: If Content Blocker was greyed out, you might accidentally enable Restrictions for Safari. So you need temporarily disabling restrictions to activate the content blocker.
You should be able to turn on your content blocker. Once you've done so, you can re-enable your Restrictions.