Yeah there is no L2TP on the Archer VR2800. But I'm not sure what you need to do with that, what do you mean by route traffic?
If you can kindly explain it, maybe there is another way to do this.

I basically want all my outbound traffic routed through a vpn
www.myip.io for example
or expressvpn.com

You'll need to use a VPN client on your local devices to facilitate this. The router acts as a VPN Server, not a VPN Client, which is what you'd need to have, for locally connected devices to be able to access the internet via a VPN. The router only provides server functionality for remote devices to connect to your local network (and / or the internet). It has no client functionality.