Is there a way that some devices can share in local network but not going online

I have got really old hardware(for example a receiver) who do not get any security updates and I am asking myself. Is there a way, that my devices can share in local network but not going online?

My network hardware is:

  • fritz box 7530 ax
  • 5 port switch

In my fritz box i can disabel a device, but I guess that it is also disabled for my local network.

I saw this post, but not a good anwser and quite old:

old post