You can use the Apple AirTag for your cat but it is advised that you should also equip your cat with a GPS tracker, just to be on the safe side.
GPS pet trackers are made specifically to track your furry friend, whereas Apple AirTag is mainly used to find other items and belongings, such as keys, phones, wallets, handbags, and backpacks. Also, the range for it is quite short and only can be detected by other IOS devices.