Brave Browser automatically blocks ads (but has their own drop down ad that shows up)
Chrome, Firefox, Opera, Safari, etc have extensions you can add that perform different functions.
For these you usually access either by going to a specific URL or through the app settings in the Settings app on your phone. Safari, for example, you go to Settings>Safari>Extensions and then look for AdGuard or ABP (AdBlockPlus). Chrome, for example, you go to their extension store:
https://chrome.google.com/webstore/ and look for ABP or AdGuard.