You can do that using tailscale, which is free.
It allows you to safely connect to computers from inside or outside your network.
Install Tailscale on both machines, then in CCC, you will use the Tailscale-assigned IP address for the remote machine as the Destination, then select a folder for the backup to be saved in.
I just tried this from my M1 MBP to my iMac Pro using CCC, and it’s working.
I’m not outside my network, but I’m using Tailscale for the connection.