There is no need to install a specific app to block porn site on your mobile. The most easy way is to turn on the Google SafeSearch. The following are detailed steps:
Step 1: Set your search engine to Google. On an iPhone, go into your phone’s settings, scroll down and tap on Safari, and then choose Google under Search Engine; in Chrome, tap or click on the three dots either at the top or bottom of the screen.
Step 2: On mobile devices, open your Google app (you may need to download it). Tap on the gear icon, scroll down and tap on Search Settings, and then tap “Filter explicit results” under SafeSearch filters. On desktops and laptops, go to www.google.com and click Settings in the bottom-right corner; click on Search Settings; and click Turn on SafeSearch and then Lock SafeSearch.
Alternatively, if you just don't want to be bothered by the popups that come from those porn sites, you can use OnlyFans, which is an online subscription-based social media platform. If you want to watch adult videos on it for free, see: How to Free Download OnlyFans Videos?