It sounds like you may want to create a VLAN and disable Inter-VLAN routing - this will prevent cross network communication. To keep devices on a wireless network from talking with each other you’ll need Layer 2 isolation. Or this can be done with an internal firewall rule. And finally, have that VLAN associated with a SSID.
Layer 2 Isolation
Internal Firewall Rule
As a note, switches can end up poking a hole in the network isolation if they are in the same network segment.