Here's a great article that goes over a lot of supplies :thumbsup
https://www.backyardchickens.com/articles/chicken-first-aid-kits-handy-and-essential-supplies-and-how-to-use-them.64830/
So far my go to that have proved extremely helpful with all my birds:
Saline Wash
Vitamin B
Nutridrench
Poultry Electrolytes
Neosporin/Bacitracin w.o pain relief
VetRx
....just to name a few :th
Good idea to stock up now though so you have it on hand if needed. I will find the article that...