You can use
different difficulties at
https://hexpool.com very easily.
Use c=BLAS,d= as your password, e.g. c=BLAS,d=4
See below for an example from Nicehash:

Example for command line option:
-a blake2s -o stratum+tcp://hexpool.com:5766 -u WALLET -p c=BLAS,d=4