Not in the common sense, we use Direct Correlation – Proof of Work (DC-PoW).
What is DC-PoW?
DC-PoW is the work (processing caches for others’ transactions) you are expected to do is equal to the number of coins you hold.
It is not an opt-in, it is a requirement. But, you can delegate your effort to someone else, who is willing to do this for you. By default, this is automatic.