Calculate all ipv6 subnets using php/laravel

I have to calculate all subnets of ipv6 using laravel /php
this is an example of what I am trying to do

the customer should provide me the prefix of the IP and length like this

$ip = ‘2407:cb00:250’;
$subnetPrefix = 64;

so I nned to generate all available subnets like this

2407:cb00:250:1/64
2407:cb00:250:2/64
2407:cb00:250:3/64 ..etc

actually, I tried a lot without success especially when the user set len to be for example 65,66,67 ..etc
are there any one can help me to get what i want or if there is any laravel library that can do the work