For example: you cannot install NoScript, or anything like it, on an iOS browser. You must choose between "all JS on" or "all JS off", and third-party browsers like Firefox are crippled because Apple forces all iOS browsers to use their WebKit engine under the hood.
The myriad of Safari "content blocker" apps are also pretty dismal, and often expensive. So ad-blocking is difficult as well.
They're better about app tracking, but you might want to keep an Android phone handy if you enjoy browsing the web.