Start reading here: Handheld Augmented Reality | Unreal Engine Documentation
Then also read about ARCore (this is for Android): Build new augmented reality experiences that seamlessly blend the digital and physical worlds
and about ARKit (this is for iOS): Apple Developer Documentation
You need a Mac for iOS.
If you are a beginner it might be a good idea to buy a book or search tutorials on Youtube and Udemy.
The example at shorturl.at/fmEO2 is called “Web AR”. Search Web AR Plugin for Unreal Engine.
Maybe there is none. Then you could make it yourself, but only if you know how to program C++ and learn a lot about Unreal Engine, not easy for beginners.
Don’t give up too fast, it is a lot to learn and it takes time, that is normal. Good luck