hdishs
Vanadium and Chromium doesn't have such a feature. You'd have to use a third-party app. RethinkDNS can do this. It requires some configuration, although it's not difficult. I just tested it and this seems like the simplest method:
Open RethinkDNS and go to Apps > Vanadium > select Isolate. Then either select Domain rules to add IP addresses and/or domains to allow, or select Domain logs to configure the domains you have recently visited.
Note that if RethinkDNS ever disconnects without the system VPN killswitch* enabled, this will have no effect. It can't be guaranteed to protect you against mistyping a URL if the VPN connection drops or the app has a bug which breaks the functionality.
*GOS settings > Network and internet > VPN > cogwheel > Always-on-VPN and Block connections without VPN