What's the difference between:
1. I hope he will like it.
I haven't given it to him yet, but when I do, I hope he likes it.
2. I had hoped he would like it.
I gave it to him and he didn't like it, but I had hoped that he would.
Do you think it is necessary for a primary 3 child to use the second one?
No - even native speakers are rarely in a situation that would require them to use this tense.