Microsoft already does this.

„Microsoft removes content that contains apparent CSEAI. As a US-based company, Microsoft reports all apparent CSEAI to the National Center for Missing and Exploited Children (NCMEC) via the CyberTipline, as required by US law. During the period of July – December 2020, Microsoft submitted 63,813 reports to NCMEC. We suspend the account(s) associated with the content we have reported to NCMEC for CSEAI or child sexual grooming violations.“

https://www.microsoft.com/en-us/corporate-responsibility/dig...