While most multi-tenant buildings offer janitorial services, single-tenant buildings may or may not come with a cleaning service. When lease rates are quoted on a gross basis, janitorial costs are usually included. If the rental rate is quoted on a net basis, janitorial services may or may not be available or included in the rent. If janitorial services are available and the rent is quoted on a net basis, the cost of cleaning will usually be over and above the rent stated in the lease document. Check your lease to be absolutely sure.
A good broker or property manager help you find outside janitorial services if you need them, but don´t rely on your broker to set it up automatically.