Right. To get what you want you'd need to be in Do Not Disturb mode and/or Ring/Silent 24/7. Keep in mind that DND does not work while your iPhone is unlocked. That doesn't mean RingerX VIP will stop working just because your iPhone is unlocked, but it makes it kind of superfluous.
You might be better served just leaving DND off (which allows calls/texts) but creating a blacklist group. Drop the contacts you don't want getting through into that blacklisted group and set RingerX VIP to just ignore calls/texts from that group. That would allow you to leave DND off and RingerX VIP would make sure that those calls and texts are ignored whether your iPhone is locked or not. This would mean that you'd have to create a contact for each number you want blocked and add that to the group.
What I just described is exactly what I am doing, except that I just have this applied to a contact, not a group. Anyone I don't want to hear from I add to my Blocked Caller contact. It's easier just to add a number to a single already existing contact which is why I do it this way. I don't have to create a new contact and add it to a blacklisted group. But if you already have pre-existing contacts you want to blacklist adding them to a silenced blacklisted group is probably easier.
In the shots below you can see that RingerX VIP is showing a mute icon, meaning that all notifications from the numbers attached to this contact are suppressed.