Grouping Ports with VPN leaving all other Ports operating as a Switch

Hi

I have a CRS125-24G-1S-2HnD-IN ( Currently used as a 24 port Switch )

my network is 192.168.1.x - 255.255.255.0
Gateway is 192.168.1.81

I need all existing items to stay working as is;

I would like to have the WiFi on this unit to operate on a alternate subnet of 192.168.20.x

Which then grouped together and is forced to use a VPN that I also need configured on this router.

NordVPN is my provider, I believe it uses OpenVPN connection, although I have never configured this to date.
Was hoping that I could have an auto reconnect, script or alike to ensure devices are connected always.

Once this is configured, is it possible to add say Network Ports 17-24 to this setup, same as the WiFi and get the same DHCP distribution and rules with VPN ? ;

Therefore Ports 1-16 would be as current operating as a switch
Ports 17-24 and WiFi grouped and on a alternate subnet 192.168.20.x with a gateway 192.168.1.81 using VPN Connection to NordVPN

I understand basic networking although this Mikrotik units are currently confusing me, they appear to be able to quite powerful in the right hands.

Any Assistance would be greatly appreciated.

Thanks