https://learn.microsoft.com/he-il/intune/configmgr/comanage/tutorial-co-manage-clients?toc=/mem/configmgr/cloud-attach/toc.json&bc=/mem/configmgr/cloud-attach/breadcrumb/toc.json
Tutorial: Enable co-management for existing clients - Configuration Manager | Microsoft Learn
Configure co-management with Microsoft Intune when you already manage Windows devices with Configuration Manager.
for existing clientsconfiguration managertutorialenablemanagement