SD Access provides a network wide fabric, which can be used for end-to-end segmentation based on policies you create.
The design of the fabric, creation of these policies and monitoring of the SD Access components is done through DNA-Center, i.e. SD Access is a network wide solution, which is managed and monitored through DNA-Center.
For more information on SDA:
Software-Defined Access - Cisco
For more information on DNA-C
Network Management and Automation - Cisco DNA Center - Cisco
Hope this helps.