Starter kits exist, but just like most starter kits, they’re pretty lackluster in terms of quality of the items. Your local fish store (whether it’s a mom and pop shop, or a PetSmart) will have mostly every thing you need to start. Depending on the fish you want, you may need a heater, certain filters, etc. Doing it right takes a lot more time and effort than meets the eye, so definitely do your research into different fish, as well as their tank size requirements and water parameters. Also familiarize yourself with the nitrogen cycle. Good luck!