If this is a one time deal, hire a photographer, or a family friend that is a photographer. Taking good photos takes skill, especially knowledge and experience with good composition and good lighting. Then there's Post Processing, but maybe your printer will do that for you. Don't buy equipment that will be used once then sit for weeks collecting dust. If you really want to do it yourself, consider renting. I use lensrentals.com. If you really want to buy, buy used. I use
KEH.com and there are some great deals on dslrs and lenses right now as people unload that gear to go mirrorless. Just know that it takes time to learn how to use a camera correctly.
You need to find out what the 24mp requirement is all about. Most printers will tell you how many pixels per inch they recommend, not the mp of the image, but maybe they backed into 24mp from your requirements. In any case, I have gotten very good results making 17" X 22" prints from 12mp cell phone jpgs, so I'm skeptical of the 24mp requirement.