If your use case is you want IoT isolation, the standard advice is to just use separate SSID's.

If you are using one of the routers that has true VLAN support like the AX86U Pro, there are anecdotal reports of people getting it to work but it's hacks and workarounds.

https://www.snbforums.com/threads/ax86u-pro-vlan.83996/

VLAN support in the AX86U (not Pro) would be a win. But it looks very hacky.

https://www.reddit.com/r/HomeNetworking/comments/l47ocn/secu...