So, if you've saved up some money from your Sim's careers or other money-making methods, you may want to start with what you have. You'd then need to pay the lot value to purchase the restaurant. First, know that unless you're cheating, building/placing one from manage worlds will not be a shortcut to ownership. This guide will teach you to build your own.
To even begin managing a restaurant in The Sims 4 Dine Out, you must first own one. The Sims 4 Dine Out Game Pack Building a Restaurant Part 1: (Lot Type Requirements) You can build your own restaurant in Dine Out, fully staff it, customize the menu, and run it.