We have F5 HA in Active -Active setup , So If I have to configure a new VIP which is in traffic-group-2 and Active in prd-bigip-t2 F5 then where I have to configure it and from where I have to sync the config ?
I would say that config-sync has nothing to do with traffic-groups or which device is active.
Preferrably you should configure it on that device, where the new configuration should be active. But at the end it's only important to use the correct "direction" for the config-sync. On the device, where you added the new configuration you have to choose "push" to device-group.
Keep in mind to not change configuration on both devices at the same time to avoid configuration conflicts (the config-sync section will inform you about this).