Yes. Open the customer in Customers, and (only when Allow Refer a Friend is enabled on Marketing > Hub) the edit form shows Cashback % (a value of -1 means 'use the global Loyalty Cashback Percentage') plus Digital Amount to Referring Customer and Digital Amount to Referred Customer, each also defaulting to -1 ('use the global value'). Per-customer values, when set to -1 or higher, take precedence over the Marketing > Hub defaults at checkout time.