I don't know why you guys kept talking about this topic, but here is my story about my parents.
My parents were born in Saudi Arabia. They are both conservative Muslims; for instance, my mother wears burqa in the United States.
How old are they? My mother is 10 years younger than him. They got married when they became adult.
In my experience, I haven't heard any issues about child marriage in Saudi Arabia. Human Right Watch doesn't say much about this topic.
I have dozens of uncles, aunts, cousins, etc, but I don't see any child marriage or early age.
However, the only thing I know is that Yemen has child bribes for a long time. Probably because of poverty and conflict. For example, when Saudi-led coalition invaded in Yemen, the child bribe has been grown rapidly, according to news reports.
Regarding holy Qur'an, there is one verse that mentioned child marriage:
"And those who no longer expect menstruation among your women – if you doubt, then their period is three months, and [also for] those who have not menstruated. And for those who are pregnant, their term is until they give birth. And whoever fears Allah – He will make for him of his matter ease." – Quran 65:4 (Sahih International Translation).
Many Muslim scholars said this verse supports child marriage, but this is questionable. Here is the link from Discover-the-Truth website about this particular verse. I urge you to read it.
https://discover-the-truth.com/2016/03/12/quran-654-the-child-marriage-claim/