I have several WiFi and PoE cameras that work just fine without and Internet connection (and if you this that is not possible, then you don’t belong in this thread).
While there was a recent “vulnerability” that would let you gain access to the cameras without requiring a full-time Internet connection, I believe that this was “fixed” in firmware 2.13.11.
This system, as designed, is not intended to be used without an active, always-on, Internet connection. The very clear intention is to only relay their information out to the Internet and then be viewable via the Blink Home Monitor mobile app (yeah, there is 2-way audio, I know …via the mobile app). There isn’t even a desktop interface. Ridiculous.
As it is, there is no way to use these camera directly on your LAN. I recommend Axis cameras for a solid network-accessible camera …but they are not cheap. I bought a 6-camera Blink system for less than a single one of my Axis cameras.