easy caller & notification set up?

The MUTE switch on the left side of the iPhone above the Volume buttons.

If you want finer control then that use Settings/Focus/Do Not Disturb.

"easy caller & notification set up?: How do I easily setup iPhone13 iOS 26 to[...]"

-------

Allowing Callers and Notifications:

"allow all callers & all notifications[....]"

Have the phone powered on, don't use filters, and increase the volume up loud enough for you to hear sounds.

Disallowing Callers and Notifications:

"disallow or switch off all callers & all notifications?"

With do not disturb, you wont get any noise, though you would see it on your screen. To stop it all, contact your Carrier, in regards to your eSIM or SIM card. Of course, turn off your phone, and you won't have any output.

"how do I turn the 'filters' off? are you referring to Focus settings? if so how do I deselect ALL callers & ALL notifications, it appears I can only do them one at a time?"

-------

Filters to Use and Why:

Filtering is permitted in numerous ways --from the Phone app itself, to using third-party apps. Malwarebytes Mobile will block out known scam numbers. Then, there is another app called "Bouncer", which allows you to filter out messages based on scenarios (i.e. keywords and phrases). A browser called Brave is a great browser to consider using for ad filters. In all, using these filters is just fine. You can even filter known contacts. Then, there is Screen Time, which you could configure use of Notifications --and on form there.

Just Curious: Why do you want to allow all items? I would think you would want some to not come in (scammers).

Reporting Scammers:

You can report these scammers by grabbing their messages' and calls' content though use of the Photos app. You'd copy items(characters) using screenshots, and paste them where applicable. Learn more at my User Tip: Using the Photos App to Report Scams: - User Tip