Whether you can access these devices or not depends on your firewall rules.

The usual (very simplifed) setup is as follows

VLANs:

• VLAN_Trusted
• VLAN_Untrusted
• VLAN_IoT

Firewall rules:

VLAN_Trusted: Can access everything, WAN (internet) as well as devices on VLAN_Untrusted and VLAN_IoT. Usually, your PC or smartphone is here

VLAN_IoT: can only access WAN (internet), but none of the other VLANs, usually connected devices, like smart appliances that you control via their dedicated apps, like Philips HUE lamps, etc

VLAN_Untrusted: Can not access anything. Usually devices that you don't want to allow to access anything, lika a TV, or a printer to prevent automatic firmware updates.

Some people also hav a VLAN_Guests, which is similar to IoT, where devices can only access the internet.

I hope this helps