As I understand, you are looking to set the value of "SNR" for determining "CQI" using "UE" and "gNB". You can refer to the following example from the "5G Toolbox" that demonstrates how to compute downlink channel state information (CSI) parameters such as CQI reported from "UE" to "gNB" as feedback:
openExample('5g/NRDownlinkCSIReportingExample')
This example utilizes the "SNR" definition found in the link below, which explains how to define "SNR" in link simulation:
Hope this helps!
