⚫️ “And [also prohibited to you are all] married women except those your right hands possess.” (Quran 4:24) You can’t take another man’s wife, but the exception is that you can sleep with married women whom your right hand possesses, meaning capturing or purchasing sex slaves. You can sleep with (ie rape) them even if they were married before you gained ownership.
⚫️ “...then marry those that please you of [other] women, two or three or four. But if you fear that you will not be just, then [marry only] one or those your right hand possesses.” (Quran 4:3) This says taking three or four wives is fine, but if you can’t be “just” to multiple wives then taking sex slaves (those whom your right hand possess) is better.
⚫️ “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. ...” (Quran 65:4) The key is the last part which reads “those who have not menstruated.” This clearly applies to girls who have not hit puberty, saying that sex is permissible after a three month waiting period. This is clear set of rules for child marriage.