Is it normal that all my devices (wired and wireless) on all my networks (main, iots and guest) are part of the subnet 192.168.68.0/24 ?

Where is the separation?

Can I force a subnet to the following:

- main (ex.: 192.168.68.0/24)

- iots (ex.: 192.168.69.0/24)

- guest (ex.: 192.168.70.0/24)

Furthermore, is it true that all the isolated iot devices can see each other? Why doesn't it isolate it completely except for the access to the internet?

I really need to understand how the routing works.

Thank you!!!

Cheers!!!