Yes it is. Lets assume you have a data LAN setup (untagged) as 192.168.50.1 that all the current pcs / laptops connect to.
Set up a VLAN for the CCTV cameras (eg VLAN 51 as 192.168.51.1/24).
Create a new SSID (eg CCTV-WIFI) in that VLAN 51. The WIFI cameras can connect to it.
If you have a dedicated POE switch with cameras powered from it, either set the port the switch connects to on the Peplink/Pepwave as an access port for VID 51, or if its a managed switch, set the ports the cameras connect to as access ports for VLAN 51.
Then set up the firewall rules that block that CCTV subnet (192.168.51.0/24) from accessing the WAN.
Devices on the data network will be able to access the internet and the cameras, the cameras won’t have internet access.