You can use a dynamic address in a policy just like any other address object. Dynamic addresses have a different icon to show that they are a Fabric connector address.
You can create a new policy in Policy & Objects > IPv4 Policy. You can select the dynamic address created in Creating an address as a source or destination in your policy.
By using the FortiGate Fabric connector for Azure, the configuration of the FortiGate’s policies does not depend on the IP addresses of the resources connecting to it. You could move the entire environment to a new Azure location on a different continent with different public IP addresses, even for internal resources. After the move, no reconfiguration needs to take place. Everything works just as it did before the move.