Can I change the IP address of "dhcp-server-port" port created when DHCP on subnet is enabled?
You can not change the IP address of dhcp-server-port.
The IP address is re-numbered by disabling DHCP -> activating in subnet configuration. Even in that case, the lowest number of unused addresses in the IP address allocation pool is automatically withdrawn, so addressing is not possible.
(Reference) Service descriptions - Logical Network