Saudi Arabia has a sovereign wealth fund with trillions of dollars. The obvious answer is that they'll build a ton of renewables and build a ton of [hydroponic/aquaponic/aeroponic/etc] farms to make food locally.
Indoor farming is expensive but very water-efficient, which suits Saudi Arabia as their water comes from expensive desalination plants.
I remember an old discussion about this. The main problem is that transmission lines to potential customers would have to traverse unfriendly countries.
https://www.bbc.com/future/article/20201112-the-green-hydrog...
Europe will need lots of those. It can very likely not be produced in Europe alone.
Even if they don't, 1/3 of the countries in the world are drenched in sunlight. The competition will make margins on these industries pretty pitiful.
But this is only possible because renewables represent only a small fraction of all power in most places. They can at peak generate a significant amount of power, but overall most produced TWh come from other sources.
If that overproduction can be channeled into e.g. hydrogen production which can be used for airline fuel or heating homes or for topping up the grid when it's not windy or sunny all the better.