The CEO/founder has three jobs.
The first one, is to provide the vision. The things that could be. By providing a vision, a leader can instill purpose into every single person in the organization.
The second, is relations, relations, relations. Customers, investors, partners. They all want to make sure they are talking to the man upstairs. This gives confidence to the market, and those helping you grow.
Finally, and in my opinion, the most important, is -as they say often- to work ON the business, not IN the business. This is what drives change and sets up an endless chain of micro pivots to drive the organization forward.
In this process, the leader -because she must NOT work IN the business- has to find capable people to take care of each function. It is one of the most paradoxical things in business. While doing so, the leader must strive to turn herself expendable, and by doing that, an indispensable leader.