I want to know is it possible to track physically or Get Information about the smartphone by just knowing its MAC address connected to our Wifi.
Yes, it is see e.g. https://ssd.eff.org/en/module/problem-mobile-phones Smartphones send their MAC address which is visible for surroundings near by, a bit like car register plate in concrete world.
But you don't know who is in the car just based on the plate and the car could be empty.
With smartphone its more likely that same person is using the machine. So if you are able to link MAC address with another personal identifier like name, phone number, SIM info then tracking is better enabled.