Well, legally speaking, that depends on where exactly you live and the local laws.
Aside from that, there are also purely practical reasons for chilren to not ride in the front seat regardless of the rules. Do note that it may be dangerous for them in the event of a collision. Especially for babies and toddlers. There is a good reason children car seats are never installed in the front seat.
To sum it all up, children can only ride in the front seat after they no longer need a booster:
https://carseatresearch.com/what-is-the-backless-booster-seat-age/ Only, it's "may", they can ride there long before that.