Hi,
The KCC automatically creates replication connections between DCs within the site.
It is usually not necessary to create manual connections when the KCC is being used to generate automatic connections; if any conditions change, the KCC automatically reconfigures the connections.
Adding manual connections when the KCC is employed can potentially increase replication traffic and conflicts with optimal settings stipulated by KCC.
But you really need to create the connection manually, you can do this through AD site and services as following:
Note that when you modify a connection object, you convert it into an administratively modified connection object and the object appears in the form of a GUID. The KCC does not make changes to manual or modified connection objects.
Following link for your reference:
https://learn.microsoft.com/en-us/windows-server/identity/ad-ds/get-started/replication/active-directory-replication-concepts#BKMK_1