I think there’s a misunderstanding. The [DHCPServer] section is tied to a [Network] unit. The [Network] unit has an address range. The [DHCPServer] section has

I think there’s a misunderstanding. The [DHCPServer] section is tied to a [Network] unit. The [Network] unit has an address range. The [DHCPServer] section has options to reserve a range for dynamic leases. There is also [DHCPServerStaticLease] sections to assign static leases. However, previous versions of networkd did not allow the static lease to be outside of the [DHCPServer] dynamic range. Now, the static lease can be outside the dynamic range but within the network range. So, pretty much what any other standard DHCP server can do.