Get them as chicks and interact with them every day.

If you do, the chickens will actively seek you out to hang out with you.

Thier coop will need regular cleaning and everything will try to eat them so you really need a coop.

I'm not sure rats will be a problem if you keep their food in a metal container. Your biggest urban threat is likely raccoons.

Couple of things to keep in mind. You likely need to get at least 6 chicks to start as most stores will not sell in smaller quantities.

Additionally, you really don't want to end up with more than a single male. To that end DO NOT get a "straight run" of unsexed chicks. If you do, expect a bloodbath.

Straight runs tend to be what is left after the chicks that could be sexed as female have already been removed.