Systems and methods provide for network-based selection of a UE device's 5G operation mode. A network device in a wireless core network receives a policy query for a user equipment (UE) device. The UE device is capable of 5G non-standalone (NSA) and 5G standalone (SA) operation modes. The network device identifies one or more of subscription data for the UE device, stored network data associated with the UE device, or dynamic network data relevant to the UE device. The network device assigns, based on the identifying, a radio access technology/frequency selection and prioritization (RFSP) value for the UE device. The network device sends the RFSP value to an access management function in the wireless core network for controlling selection of the 5G NSA operation mode or 5G SA operation mode.