Is it possible to hide the wifi network SSID on a Orbi RBR860 router?

No.  The original WiFi5 Orbi had that feature, but it was never available on any of the WiFi6 routers.

Not broadcasting the WiFi SSID was a popular security measure a decade ago.  It no longer is.

If there is a reason to want to hide the SSID, there may be other solutions than hiding the SSID.