Few Questions about parental blocks w ethernet jacks/wifi

Ethernet jacks can't be individually controlled through the router itself. No residential router that I know of has that feature. You can get a physical kill switch for individual lines but you would need to physically flip the switch. Their reliability is unknown.

Wifi is controllable to a point but there are caveats. One big problem you will experience is devices changing their MAC addresses on their own. This means that if you restrict one MAC address and the device switches to a different one, the restrictions would no longer apply. Windows 10 and 11 both give the option to rotate or change the MAC or hardware address when connecting. Many cell phones and tablets also have the same feature.