This right here. What is your intended use. Fun at the range? Personal defense ( concealed carry) home defense?
The most important thing right now that is universal, regardless of your intended use, is at least a basic pistol safety course. Check local ranges or ask a trusted friend or Law Enforcement Officer. In this course you will learn how to properly and safely shoot, clean, load, store and handle your firearm. If I were you I might look into a concealed carry class because you will ( or should anyway) learn all those things in that class and as a bonus take care of the qualifications needed to obtain a concealed carry permit.
Other than extra magazines, an Uplula loader and quality target ammunition I would hold off on buying too much stuff just yet. Particularly I wouldn't buy a holster yet because running out and buying a holster based on your very limited knowledge of guns in general and that gun in particular is the very best way to start your collection of unused holsters that wind up taking space in a drawer somewhere. Don't cheap out on the magazines either. Lots of people have good luck with Mec-Gar aftermarket mags, but I would never buy one as long as Wilson, Chip McCormick, Ed Brown or even Kimber produced magazines for my gun. Decent electronic ear muffs are a must and a good pair of safety glasses.
Welcome to the forum from Missouri.