No.
VPN based system-wide adblockers are being hunted by Apple. Most of them have ceased to operate by installing a fake VPN (the one that works entirely inside your own device) and, as a workaround, are working now through DNS servers from those adblockers companies.
An example is AdGuard Pro. It used to work as a fake VPN, but now it's just a custom DNS installer that, as a paid app, allows you to make your device connect to custom DNS servers through cellular network (remember that iOS, by default, only gives you option to insert custom DNS in Wi-Fi networks, not cellular).
The remaining apps that install fake VPN servers inside your own phone will be shut down by Apple eventually (Apple has changed their App Store rules and now fake VPN apps are forbidden).
As for DNS adblockers, they work well in most cases, although not as good as fake VPN adblockers. However, neither fake VPN nor adblocker DNS server can block some apps ads, like Facebook, YouTube, Instagram. That's because those apps download ads in a cryptographic algorithm and from the same servers that provide the app content itself, making it impossible for adblockers to intercept them.
But, good guy Apple provides iOS with the Safari Content Blocker API, which allows apps that use it to block ads from basically every website (including the ones from Facebook, YouTube and Instagram). In other words, you can block ads from those services, but only when you use them through a web browser with adblocker in iOS.
Because of this, I don't have YouTube and Facebook apps in my iPhone. I still use Instagram, because their ads aren't retardedly invasive.
I would use Facebook app if it (just like it's Android brother) allowed me to set it to open links in Safari by default. The iOS version of Facebook app forces you to open every link through it's built-in web browser, that doesn't use Safari Content Blocker API. I know I can manually click the option to open the page in Safari, but having to do that for EVERY link is unacceptable.
This is the adblocker that I use for Safari:
https://itunes.apple.com/br/app/adb...aster-without-tracking/id1028871868?l=en&mt=8