Depends on the hardware, even consumer networking hardware often support VLANs. Sometimes it's hidden behind settings, other times you'll have to use something

Depends on the hardware, even consumer networking hardware often support VLANs. Sometimes it's hidden behind settings, other times you'll have to use something like OpenWRT. Some hardware lets you run multiple APs at once, and you can have an AP for your VLAN. Sometimes it's cheaper/easier to just buy a shitty router to use for your untrusted devices.