As far as I know, pronouns such as "it" cannot be modified like "beautiful it". However, from my experience, I have heard native speakers say things like "Enjoy it with your dog", which I believe the pronoun "it" is being modified by prepositional phrases or relative clauses however I am not so sure. So my question is "Is it possible to modify a pronoun such as 'it' with a prepositional phrases or relative clauses?? I'll list more examples below thank you.
1."What is it that you don't understand about the problem"? 2. "Did you enjoy it at the restaurant?" 3. "What is it with you!"