That would depend on what you mean actually. This sounds a bit specific. If you’re looking to make an online food ordering and delivery app, some good features to include would be multiple payment options, multiple languages, an easy interface, wallet system, real-time restaurant status, etc. If you mean a specific app for restaurants, meaning with the dashboards and everything, the answer would differ a little. Either way, the best thing I would suggest is using an ubereats clone app. These uber eats clones have all the features already built-in and come with apps for restaurants, admins, and customers.
This way you wouldn’t break the bank, which you might have to if you make the app from scratch. This is not a small task and would require hard work from multiple developers. If you are looking for a good clone, a simple good search would sort you out. Many companies provide uber eats clones nowadays. Just make sure that you find a company that is well-experienced in doing this kind of thing. They should help you out with future software updates and also get the app on the relevant app stores. Hope this helps.