Both mentions
The first comes at the end of a long list of prophets in Surah al-An'am: And Isma'il and Al-Yasa' and Yunus and Lut — and all of them We preferred over the worlds (6:86).
The second: And remember Isma'il, Al-Yasa' and Dhul-Kifl, and all are among the outstanding (38:48).
Read the first one in context if you can. It comes at the end of a passage naming Ibrahim, Ishaq, Ya'qub, Nuh, Dawud, Sulayman, Ayyub, Yusuf, Musa, Harun, Zakariya, Yahya, 'Isa and Ilyas — and then Isma'il, Al-Yasa', Yunus and Lut. A child who has been through these stories will recognise almost every name, which makes the list itself feel like an ending.
Telling a story with no story in it
There are three prophets like this — Idris, Dhul-Kifl and Al-Yasa'. Told together, they make a point that none of them makes alone.
The Quran is not a complete history. It tells at length what is needed and names the rest. A child who understands that early will read it better for the rest of their life, and will not be thrown when they discover that a favourite detail came from somewhere else.
There is also a plain comfort in these three. Whatever Al-Yasa' did, nobody wrote it down and it was not lost. He is named among those preferred over the worlds, and no story was required for that to be true.
The list he appears in, in full
Because 6:83-86 is the passage he is named in, and because it gathers up most of the prophets a child will have met by now, it is worth reading straight through. In order, it names: Ibrahim, then Ishaq and Ya'qub, then Nuh, and of his descendants Dawud, Sulayman, Ayyub, Yusuf, Musa and Harun; then Zakariya, Yahya, 'Isa and Ilyas — all among the righteous; and then Isma'il, Al-Yasa', Yunus and Lut — and all of them We preferred over the worlds.
That is eighteen prophets in four verses. If your child has worked through these stories, read it to them and let them count how many they recognise. It is the best possible ending to the whole set, and it takes thirty seconds.
The passage then says something about all of them together: And We chose them and guided them to a straight path (6:87). Not each one separately for his own achievement — all of them, chosen and guided. The ones with long stories and the ones with none are in the same sentence.