Possible to make Raspberry Pi 3 as Wifi hub?

Is it possible to make Raspberry Pi 3 work as “Wifi hub”, so all wifi devices will be on separate network, and the Pi itself will connect to my main router also through Wifi?

This will eliminate dependency of connection from router, when my router lose internet its freezing or something and there is no internal lan, so I though getting another router for stable internal network but maybe it’s possible for Pi do it

Yep it is but not tried both for wifi HASS.IO wifi hotspot
only thing I’m missing is either bridge the networks to allow the devices to access the internet hence ntp servers etc or find a relay component
Mark