@danklim
I don't know if this will fulfill all your needs, but you can use Do Not Disturb and its options.
In settings > Do Not Disturb > Allow Calls From > and here you have a number of choices. If you select Favourites, then ONLY calls from Favourites can get through.
For this to work, of course, you have to mark which numbers from within Contacts that you would be happy to receive a call from. They don't have to be favourites in the familiar sense, simply calls, say, business, work related (and no doubt family as well).
You can amend this list, adding or deleting, very easily. So, if on a particular day, you wouldn't want to miss a call from a shop, estate agent, car insurance firm etc, just make sure these numbers are in Contacts and add them as favourites. Remove them from Favourites when you no longer need them.
Another option under the Do Not Disturb heading is turning on "Repeated Calls". This is really only for family or close friends. You tell them, if it's urgent, to phone you twice within 3 minutes. The first call is blocked , the second gets through.
So there are some ideas that might be worth considering.
Ian