On iOS, the only way to block ads and trackers system-wide is to use DNS filtering. First, you have to enable DNS protection. To do so, open AdGuard for iOS settings —> DNS protection and switch it on.
Now, if your purpose is to block ads and trackers system-wide, you have two options:
The second option takes a bit more time to set up but has several advantages:
How DNS filtering works
You can add any DNS filter or hosts file, the instruction will be the same for all of them. For the sake of the example, let's add AdGuard DNS filter. It is composed of several other filters (AdGuard Base filter, Social Media filter, Tracking Protection filter, Mobile Ads filter, EasyList, EasyPrivacy, etc.) and it's simplified specifically to be better compatible with DNS-level ad blocking.
Note: We don't recommend touching other settings you'll find inside the Advanced settings tab, especially when it comes to Low-level settings. Some of them might break the Internet connection or compromise your privacy and security, so it's better to be careful. The text below describes the exact actions required to add AdGuard DNS filter.
Add any number of other DNS filters the same way by pasting a different URL at step 3. You can find various filters and links to them here.