Do you mean does a Solo card debit money straight from your account? If so, then yes, each time you use the card the bank authorises the transaction there and then and the money is effectively debited to your account. A Direct Debit is something different, it is a regular pament deducted from your account directly by a company, and it can be set up on most current accounts.
Bank accounts allow solo cards and bank accounts allow direct debits so indirectly you may get a direct debit, although it is unrelated to your card.
I'm making a bit of a leap here but through a Solo card you can have a subscrption to people like an internet ISP which goes out automatically each month. In this sense, this resembles a direct debit.
Does this answer your question or can you clarify further?