Fully different with 128 bit UUID for service and characteristic


I'm creating the customize service and characteristic for my needed, but I need a full 128 bit UUID that which is different in service and each characteristic.

As I follow the tutorial or other example, the service or characteristic are using a base 128 bit UUID, and the service or each character only change the 16 bit UUID parts.

But that's not what I want, is there possible that can customize a fully different UUID for service and characteristic?