Single:
tailscale up –advertise-routes=192.168.2.0/24
Multiple:
tailscale up –advertise-routes=192.168.2.0/24,198.51.100.0/24
Note: Tailscale on Mac and Linux likely run as root, so it would have to be run via your superuser. Besides that, the process is the same for Mac, Linux, and Windows.
Note: Tailscale subnet routes must be approved via the Admin dashboard after adding them.